From a2cece84f1e37d5594d3e8562b2628939eda18a9 Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Wed, 4 Dec 2024 21:56:28 +0100
Subject: [PATCH 01/14] - initiate drag from inside
 `ctx.select_hovered_on_click()` - add `undraggable_items` to `ViewerContext`
 and populate with root container

---
 Cargo.lock                                    |  22 ++--
 Cargo.toml                                    |  14 +--
 .../re_blueprint_tree/src/blueprint_tree.rs   | 109 ++++++++++--------
 crates/viewer/re_data_ui/src/instance_path.rs |   2 +-
 crates/viewer/re_data_ui/src/item_ui.rs       |   2 +-
 .../re_selection_panel/src/selection_panel.rs |   4 +-
 .../src/space_view_class.rs                   |   1 +
 .../src/dataframe_ui.rs                       |   3 +-
 .../viewer/re_space_view_graph/src/ui/draw.rs |   5 +-
 .../re_space_view_map/src/map_space_view.rs   |   1 +
 .../re_space_view_spatial/src/picking_ui.rs   |   2 +-
 .../src/space_view_class.rs                   |   2 +-
 crates/viewer/re_time_panel/src/lib.rs        |   4 +-
 crates/viewer/re_viewer/src/app_state.rs      |  14 ++-
 .../re_viewer/src/ui/recordings_panel.rs      |   2 +-
 .../viewer/re_viewer_context/src/contents.rs  |  10 +-
 .../re_viewer_context/src/drag_and_drop.rs    | 105 +++++++++++++++++
 crates/viewer/re_viewer_context/src/lib.rs    |   2 +
 .../re_viewer_context/src/selection_state.rs  |  14 +++
 .../src/space_view/view_context.rs            |  10 --
 .../re_viewer_context/src/test_context.rs     |   3 +
 .../re_viewer_context/src/viewer_context.rs   |  40 ++++++-
 crates/viewer/re_viewport/src/viewport_ui.rs  |   2 +-
 .../src/color_coordinates_space_view.rs       |   6 +-
 24 files changed, 282 insertions(+), 97 deletions(-)
 create mode 100644 crates/viewer/re_viewer_context/src/drag_and_drop.rs

diff --git a/Cargo.lock b/Cargo.lock
index 13ed1656b5ba..5f7eabcdb372 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1923,7 +1923,7 @@ checksum = "0d6ef0072f8a535281e4876be788938b528e9a1d43900b82c2569af7da799125"
 [[package]]
 name = "ecolor"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=577ee8d22810752540636febac5660a5119c6550#577ee8d22810752540636febac5660a5119c6550"
+source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
 dependencies = [
  "bytemuck",
  "color-hex",
@@ -1940,7 +1940,7 @@ checksum = "18aade80d5e09429040243ce1143ddc08a92d7a22820ac512610410a4dd5214f"
 [[package]]
 name = "eframe"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=577ee8d22810752540636febac5660a5119c6550#577ee8d22810752540636febac5660a5119c6550"
+source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
 dependencies = [
  "ahash",
  "bytemuck",
@@ -1979,7 +1979,7 @@ dependencies = [
 [[package]]
 name = "egui"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=577ee8d22810752540636febac5660a5119c6550#577ee8d22810752540636febac5660a5119c6550"
+source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
 dependencies = [
  "accesskit",
  "ahash",
@@ -1996,7 +1996,7 @@ dependencies = [
 [[package]]
 name = "egui-wgpu"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=577ee8d22810752540636febac5660a5119c6550#577ee8d22810752540636febac5660a5119c6550"
+source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
 dependencies = [
  "ahash",
  "bytemuck",
@@ -2015,7 +2015,7 @@ dependencies = [
 [[package]]
 name = "egui-winit"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=577ee8d22810752540636febac5660a5119c6550#577ee8d22810752540636febac5660a5119c6550"
+source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
 dependencies = [
  "accesskit_winit",
  "ahash",
@@ -2057,7 +2057,7 @@ dependencies = [
 [[package]]
 name = "egui_extras"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=577ee8d22810752540636febac5660a5119c6550#577ee8d22810752540636febac5660a5119c6550"
+source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
 dependencies = [
  "ahash",
  "egui",
@@ -2074,7 +2074,7 @@ dependencies = [
 [[package]]
 name = "egui_glow"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=577ee8d22810752540636febac5660a5119c6550#577ee8d22810752540636febac5660a5119c6550"
+source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
 dependencies = [
  "ahash",
  "bytemuck",
@@ -2092,7 +2092,7 @@ dependencies = [
 [[package]]
 name = "egui_kittest"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=577ee8d22810752540636febac5660a5119c6550#577ee8d22810752540636febac5660a5119c6550"
+source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
 dependencies = [
  "dify",
  "egui",
@@ -2161,7 +2161,7 @@ checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
 [[package]]
 name = "emath"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=577ee8d22810752540636febac5660a5119c6550#577ee8d22810752540636febac5660a5119c6550"
+source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
 dependencies = [
  "bytemuck",
  "serde",
@@ -2277,7 +2277,7 @@ dependencies = [
 [[package]]
 name = "epaint"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=577ee8d22810752540636febac5660a5119c6550#577ee8d22810752540636febac5660a5119c6550"
+source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
 dependencies = [
  "ab_glyph",
  "ahash",
@@ -2296,7 +2296,7 @@ dependencies = [
 [[package]]
 name = "epaint_default_fonts"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=577ee8d22810752540636febac5660a5119c6550#577ee8d22810752540636febac5660a5119c6550"
+source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
 
 [[package]]
 name = "equivalent"
diff --git a/Cargo.toml b/Cargo.toml
index 3a0ad88ae8cd..05ddd0ae4b8d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -559,13 +559,13 @@ significant_drop_tightening = "allow" # An update of parking_lot made this trigg
 # As a last resport, patch with a commit to our own repository.
 # ALWAYS document what PR the commit hash is part of, or when it was merged into the upstream trunk.
 
-ecolor = { git = "https://github.com/emilk/egui.git", rev = "577ee8d22810752540636febac5660a5119c6550" }       # egui master 2024-12-04
-eframe = { git = "https://github.com/emilk/egui.git", rev = "577ee8d22810752540636febac5660a5119c6550" }       # egui master 2024-12-04
-egui = { git = "https://github.com/emilk/egui.git", rev = "577ee8d22810752540636febac5660a5119c6550" }         # egui master 2024-12-04
-egui_extras = { git = "https://github.com/emilk/egui.git", rev = "577ee8d22810752540636febac5660a5119c6550" }  # egui master 2024-12-04
-egui_kittest = { git = "https://github.com/emilk/egui.git", rev = "577ee8d22810752540636febac5660a5119c6550" } # egui master 2024-12-04
-egui-wgpu = { git = "https://github.com/emilk/egui.git", rev = "577ee8d22810752540636febac5660a5119c6550" }    # egui master 2024-12-04
-emath = { git = "https://github.com/emilk/egui.git", rev = "577ee8d22810752540636febac5660a5119c6550" }        # egui master 2024-12-04
+ecolor = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }       # egui master 2024-12-04
+eframe = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }       # egui master 2024-12-04
+egui = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }         # egui master 2024-12-04
+egui_extras = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }  # egui master 2024-12-04
+egui_kittest = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" } # egui master 2024-12-04
+egui-wgpu = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }    # egui master 2024-12-04
+emath = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }        # egui master 2024-12-04
 
 # Useful while developing:
 # ecolor = { path = "../../egui/crates/ecolor" }
diff --git a/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs b/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
index b6ea2ae356d4..62efc89ede41 100644
--- a/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
+++ b/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
@@ -10,7 +10,7 @@ use re_types::blueprint::components::Visible;
 use re_ui::{drag_and_drop::DropTarget, list_item, ContextExt as _, DesignTokens, UiExt as _};
 use re_viewer_context::{
     contents_name_style, icon_for_container_kind, CollapseScope, Contents, DataResultNodeOrPath,
-    SystemCommandSender,
+    DragAndDropPayload, SystemCommandSender,
 };
 use re_viewer_context::{
     ContainerId, DataQueryResult, DataResultNode, HoverHighlight, Item, SpaceViewId, ViewerContext,
@@ -168,7 +168,7 @@ impl BlueprintTree {
         let item_response = ui
             .list_item()
             .selected(ctx.selection().contains_item(&item))
-            .draggable(false)
+            .draggable(true) // allowed for consistency but results in an invalid drag
             .drop_target_style(self.is_candidate_drop_parent_container(&container_id))
             .show_flat(
                 ui,
@@ -189,7 +189,7 @@ impl BlueprintTree {
             SelectionUpdateBehavior::UseSelection,
         );
         self.scroll_to_me_if_needed(ui, &item, &item_response);
-        ctx.select_hovered_on_click(&item_response, item);
+        ctx.select_hovered_on_click(&item_response, item, true);
 
         self.handle_root_container_drag_and_drop_interaction(
             viewport,
@@ -270,12 +270,11 @@ impl BlueprintTree {
             SelectionUpdateBehavior::UseSelection,
         );
         self.scroll_to_me_if_needed(ui, &item, &response);
-        ctx.select_hovered_on_click(&response, item);
+        ctx.select_hovered_on_click(&response, item, true);
 
         viewport.set_content_visibility(ctx, &content, visible);
 
         self.handle_drag_and_drop_interaction(
-            ctx,
             viewport,
             ui,
             content,
@@ -410,13 +409,12 @@ impl BlueprintTree {
             SelectionUpdateBehavior::UseSelection,
         );
         self.scroll_to_me_if_needed(ui, &item, &response);
-        ctx.select_hovered_on_click(&response, item);
+        ctx.select_hovered_on_click(&response, item, true);
 
         let content = Contents::SpaceView(*space_view_id);
 
         viewport.set_content_visibility(ctx, &content, visible);
         self.handle_drag_and_drop_interaction(
-            ctx,
             viewport,
             ui,
             content,
@@ -498,6 +496,7 @@ impl BlueprintTree {
 
         let list_item = ui
             .list_item()
+            .draggable(true)
             .selected(is_selected)
             .force_hovered(is_item_hovered);
 
@@ -603,7 +602,7 @@ impl BlueprintTree {
             SelectionUpdateBehavior::UseSelection,
         );
         self.scroll_to_me_if_needed(ui, &item, &response);
-        ctx.select_hovered_on_click(&response, item);
+        ctx.select_hovered_on_click(&response, item, true);
     }
 
     /// Add a button to trigger the addition of a new space view or container.
@@ -643,16 +642,21 @@ impl BlueprintTree {
         response: &egui::Response,
     ) {
         //
-        // check if a drag is in progress and set the cursor accordingly
+        // check if a drag with acceptable content is in progress
         //
 
-        let Some(dragged_item_id) = egui::DragAndDrop::payload(ui.ctx()).map(|payload| *payload)
+        let Some(dragged_payload) = egui::DragAndDrop::payload::<DragAndDropPayload>(ui.ctx())
         else {
-            // nothing is being dragged, so nothing to do
             return;
         };
 
-        ui.ctx().set_cursor_icon(egui::CursorIcon::Grabbing);
+        let DragAndDropPayload::Contents {
+            contents: dragged_contents,
+        } = dragged_payload.as_ref()
+        else {
+            // nothing we care about is being dragged
+            return;
+        };
 
         //
         // find the drop target
@@ -675,13 +679,12 @@ impl BlueprintTree {
         );
 
         if let Some(drop_target) = drop_target {
-            self.handle_drop_target(viewport, ui, dragged_item_id, &drop_target);
+            self.handle_contents_drop_target(viewport, ui, dragged_contents, &drop_target);
         }
     }
 
     fn handle_drag_and_drop_interaction(
         &mut self,
-        ctx: &ViewerContext<'_>,
         viewport: &ViewportBlueprint,
         ui: &egui::Ui,
         contents: Contents,
@@ -689,25 +692,21 @@ impl BlueprintTree {
         body_response: Option<&egui::Response>,
     ) {
         //
-        // initiate drag and force single-selection
-        //
-
-        if response.drag_started() {
-            ctx.selection_state().set_selection(contents.as_item());
-            egui::DragAndDrop::set_payload(ui.ctx(), contents);
-        }
-
-        //
-        // check if a drag is in progress and set the cursor accordingly
+        // check if a drag with acceptable content is in progress
         //
 
-        let Some(dragged_item_id) = egui::DragAndDrop::payload(ui.ctx()).map(|payload| *payload)
+        let Some(dragged_payload) = egui::DragAndDrop::payload::<DragAndDropPayload>(ui.ctx())
         else {
-            // nothing is being dragged, so nothing to do
             return;
         };
 
-        ui.ctx().set_cursor_icon(egui::CursorIcon::Grabbing);
+        let DragAndDropPayload::Contents {
+            contents: dragged_contents,
+        } = dragged_payload.as_ref()
+        else {
+            // nothing we care about is being dragged
+            return;
+        };
 
         //
         // find our parent, our position within parent, and the previous container (if any)
@@ -759,7 +758,7 @@ impl BlueprintTree {
         );
 
         if let Some(drop_target) = drop_target {
-            self.handle_drop_target(viewport, ui, dragged_item_id, &drop_target);
+            self.handle_contents_drop_target(viewport, ui, dragged_contents, &drop_target);
         }
     }
 
@@ -770,16 +769,21 @@ impl BlueprintTree {
         empty_space: egui::Rect,
     ) {
         //
-        // check if a drag is in progress and set the cursor accordingly
+        // check if a drag with acceptable content is in progress
         //
 
-        let Some(dragged_item_id) = egui::DragAndDrop::payload(ui.ctx()).map(|payload| *payload)
+        let Some(dragged_payload) = egui::DragAndDrop::payload::<DragAndDropPayload>(ui.ctx())
         else {
-            // nothing is being dragged, so nothing to do
             return;
         };
 
-        ui.ctx().set_cursor_icon(egui::CursorIcon::Grabbing);
+        let DragAndDropPayload::Contents {
+            contents: dragged_contents,
+        } = dragged_payload.as_ref()
+        else {
+            // nothing we care about is being dragged
+            return;
+        };
 
         //
         // prepare a drop target corresponding to "insert last in root container"
@@ -795,25 +799,30 @@ impl BlueprintTree {
                 usize::MAX,
             );
 
-            self.handle_drop_target(viewport, ui, dragged_item_id, &drop_target);
+            self.handle_contents_drop_target(viewport, ui, dragged_contents, &drop_target);
         }
     }
 
-    fn handle_drop_target(
+    fn handle_contents_drop_target(
         &mut self,
         viewport: &ViewportBlueprint,
         ui: &Ui,
-        dragged_item_id: Contents,
+        dragged_contents: &[Contents],
         drop_target: &DropTarget<Contents>,
     ) {
-        // We cannot allow the target location to be "inside" the dragged item, because that would amount moving
-        // myself inside of me.
-        if let Contents::Container(dragged_container_id) = &dragged_item_id {
-            if viewport
-                .is_contents_in_container(&drop_target.target_parent_id, dragged_container_id)
-            {
-                return;
+        // We cannot allow the target location to be "inside" any of the dragged items, because that
+        // would amount to moving myself inside of me.
+        if dragged_contents.iter().any(|dragged_contents| {
+            if let Contents::Container(dragged_container_id) = dragged_contents {
+                if viewport
+                    .is_contents_in_container(&drop_target.target_parent_id, dragged_container_id)
+                {
+                    return true;
+                }
             }
+            false
+        }) {
+            return;
         }
 
         ui.painter().hline(
@@ -828,11 +837,17 @@ impl BlueprintTree {
         };
 
         if ui.input(|i| i.pointer.any_released()) {
-            viewport.move_contents(
-                dragged_item_id,
-                target_container_id,
-                drop_target.target_position_index,
-            );
+            for (idx, content) in dragged_contents.iter().enumerate() {
+                // TODO: this is not strictly correct when dragging multiple items inside the same
+                // container, as the position are all over the place when moving items incrementally.
+                // We probably need a `viewport.move_multiple_contents()` method which handles this
+                // correctly.
+                viewport.move_contents(
+                    *content,
+                    target_container_id,
+                    drop_target.target_position_index + idx,
+                );
+            }
 
             egui::DragAndDrop::clear_payload(ui.ctx());
         } else {
diff --git a/crates/viewer/re_data_ui/src/instance_path.rs b/crates/viewer/re_data_ui/src/instance_path.rs
index 7dd2d6b9026d..887b02a4df5f 100644
--- a/crates/viewer/re_data_ui/src/instance_path.rs
+++ b/crates/viewer/re_data_ui/src/instance_path.rs
@@ -243,7 +243,7 @@ fn component_list_ui(
             });
 
             if interactive {
-                ctx.select_hovered_on_click(&response, item);
+                ctx.select_hovered_on_click(&response, item, false);
             }
         }
     });
diff --git a/crates/viewer/re_data_ui/src/item_ui.rs b/crates/viewer/re_data_ui/src/item_ui.rs
index 0bafd68873a2..12625645bb3c 100644
--- a/crates/viewer/re_data_ui/src/item_ui.rs
+++ b/crates/viewer/re_data_ui/src/item_ui.rs
@@ -596,7 +596,7 @@ pub fn cursor_interact_with_selectable(
     let is_item_hovered =
         ctx.selection_state().highlight_for_ui_element(&item) == HoverHighlight::Hovered;
 
-    ctx.select_hovered_on_click(&response, item);
+    ctx.select_hovered_on_click(&response, item, false);
     // TODO(andreas): How to deal with shift click for selecting ranges?
 
     if is_item_hovered {
diff --git a/crates/viewer/re_selection_panel/src/selection_panel.rs b/crates/viewer/re_selection_panel/src/selection_panel.rs
index 0930de663823..aede775a7118 100644
--- a/crates/viewer/re_selection_panel/src/selection_panel.rs
+++ b/crates/viewer/re_selection_panel/src/selection_panel.rs
@@ -656,7 +656,7 @@ fn list_existing_data_blueprints(
 
                 // We don't use item_ui::cursor_interact_with_selectable here because the forced
                 // hover background is distracting and not useful.
-                ctx.select_hovered_on_click(&response, item);
+                ctx.select_hovered_on_click(&response, item, false);
             }
         }
     }
@@ -907,7 +907,7 @@ fn show_list_item_for_container_child(
         &response,
         SelectionUpdateBehavior::Ignore,
     );
-    ctx.select_hovered_on_click(&response, item);
+    ctx.select_hovered_on_click(&response, item, false);
 
     if remove_contents {
         viewport.mark_user_interaction(ctx);
diff --git a/crates/viewer/re_space_view_bar_chart/src/space_view_class.rs b/crates/viewer/re_space_view_bar_chart/src/space_view_class.rs
index bb55311d7e39..729d23ac4e4f 100644
--- a/crates/viewer/re_space_view_bar_chart/src/space_view_class.rs
+++ b/crates/viewer/re_space_view_bar_chart/src/space_view_class.rs
@@ -248,6 +248,7 @@ Display a 1D tensor as a bar chart.
                         query.space_view_id,
                         entity_path.clone().into(),
                     ),
+                    false,
                 );
             }
         });
diff --git a/crates/viewer/re_space_view_dataframe/src/dataframe_ui.rs b/crates/viewer/re_space_view_dataframe/src/dataframe_ui.rs
index 45956a268792..88f1f4d849a0 100644
--- a/crates/viewer/re_space_view_dataframe/src/dataframe_ui.rs
+++ b/crates/viewer/re_space_view_dataframe/src/dataframe_ui.rs
@@ -261,7 +261,7 @@ impl egui_table::TableDelegate for DataframeTableDelegate<'_> {
                             egui::Rect::from_min_size(pos, size),
                             egui::SelectableLabel::new(is_selected, galley),
                         );
-                        self.ctx.select_hovered_on_click(&response, item);
+                        self.ctx.select_hovered_on_click(&response, item, false);
 
                         // TODO(emilk): expand column(s) to make sure the text fits (requires egui_table fix).
                     }
@@ -324,6 +324,7 @@ impl egui_table::TableDelegate for DataframeTableDelegate<'_> {
                                     re_viewer_context::Item::ComponentPath(
                                         component_column_descriptor.component_path(),
                                     ),
+                                    false,
                                 );
                             }
                         }
diff --git a/crates/viewer/re_space_view_graph/src/ui/draw.rs b/crates/viewer/re_space_view_graph/src/ui/draw.rs
index 21ab773bafa0..24e393687677 100644
--- a/crates/viewer/re_space_view_graph/src/ui/draw.rs
+++ b/crates/viewer/re_space_view_graph/src/ui/draw.rs
@@ -289,7 +289,7 @@ pub fn draw_graph(
                     InstancePath::instance(entity_path.clone(), instance.instance_index);
                 ctx.select_hovered_on_click(
                     &response,
-                    Item::DataResult(query.space_view_id, instance_path.clone()),
+                    Item::DataResult(query.space_view_id, instance_path.clone(), false),
                 );
 
                 response = response.on_hover_ui_at_pointer(|ui| {
@@ -336,7 +336,8 @@ pub fn draw_graph(
             let instance_path = InstancePath::entity_all(entity_path.clone());
             ctx.select_hovered_on_click(
                 &resp,
-                vec![(Item::DataResult(query.space_view_id, instance_path), None)].into_iter(),
+                Item::DataResult(query.space_view_id, instance_path),
+                false,
             );
         }
     }
diff --git a/crates/viewer/re_space_view_map/src/map_space_view.rs b/crates/viewer/re_space_view_map/src/map_space_view.rs
index 2700a4b3b93d..481b55748324 100644
--- a/crates/viewer/re_space_view_map/src/map_space_view.rs
+++ b/crates/viewer/re_space_view_map/src/map_space_view.rs
@@ -484,6 +484,7 @@ fn handle_ui_interactions(
         ctx.select_hovered_on_click(
             &map_response,
             Item::DataResult(query.space_view_id, instance_path.clone()),
+            false,
         );
 
         // double click selects the entire entity
diff --git a/crates/viewer/re_space_view_spatial/src/picking_ui.rs b/crates/viewer/re_space_view_spatial/src/picking_ui.rs
index bfd8e096fb88..e9962df58a26 100644
--- a/crates/viewer/re_space_view_spatial/src/picking_ui.rs
+++ b/crates/viewer/re_space_view_spatial/src/picking_ui.rs
@@ -209,7 +209,7 @@ pub fn picking(
         });
     };
 
-    ctx.select_hovered_on_click(&response, hovered_items.into_iter());
+    ctx.select_hovered_on_click(&response, hovered_items.into_iter(), false);
 
     Ok(response)
 }
diff --git a/crates/viewer/re_space_view_time_series/src/space_view_class.rs b/crates/viewer/re_space_view_time_series/src/space_view_class.rs
index 2b1b8581ca1d..c01ab1ece767 100644
--- a/crates/viewer/re_space_view_time_series/src/space_view_class.rs
+++ b/crates/viewer/re_space_view_time_series/src/space_view_class.rs
@@ -536,7 +536,7 @@ Display time series data in a plot.
                     }
                 })
             {
-                ctx.select_hovered_on_click(&response, hovered);
+                ctx.select_hovered_on_click(&response, hovered, false);
             }
         }
 
diff --git a/crates/viewer/re_time_panel/src/lib.rs b/crates/viewer/re_time_panel/src/lib.rs
index 8cb1807522a6..39dd59764cdb 100644
--- a/crates/viewer/re_time_panel/src/lib.rs
+++ b/crates/viewer/re_time_panel/src/lib.rs
@@ -726,7 +726,7 @@ impl TimePanel {
             &response,
             SelectionUpdateBehavior::UseSelection,
         );
-        ctx.select_hovered_on_click(&response, item.to_item());
+        ctx.select_hovered_on_click(&response, item.to_item(), false);
 
         let is_closed = body_response.is_none();
         let response_rect = response.rect;
@@ -854,7 +854,7 @@ impl TimePanel {
                     &response,
                     SelectionUpdateBehavior::UseSelection,
                 );
-                ctx.select_hovered_on_click(&response, item.to_item());
+                ctx.select_hovered_on_click(&response, item.to_item(), false);
 
                 let response_rect = response.rect;
 
diff --git a/crates/viewer/re_viewer/src/app_state.rs b/crates/viewer/re_viewer/src/app_state.rs
index 36d6d5cebe78..63514bf11c64 100644
--- a/crates/viewer/re_viewer/src/app_state.rs
+++ b/crates/viewer/re_viewer/src/app_state.rs
@@ -8,9 +8,10 @@ use re_smart_channel::ReceiveSet;
 use re_types::blueprint::components::PanelState;
 use re_ui::{ContextExt as _, DesignTokens};
 use re_viewer_context::{
-    AppOptions, ApplicationSelectionState, BlueprintUndoState, CommandSender, ComponentUiRegistry,
-    PlayState, RecordingConfig, SpaceViewClassExt as _, SpaceViewClassRegistry, StoreContext,
-    StoreHub, SystemCommandSender as _, ViewStates, ViewerContext,
+    drag_and_drop_payload_cursor_ui, AppOptions, ApplicationSelectionState, BlueprintUndoState,
+    CommandSender, ComponentUiRegistry, PlayState, RecordingConfig, SpaceViewClassExt as _,
+    SpaceViewClassRegistry, StoreContext, StoreHub, SystemCommandSender as _, ViewStates,
+    ViewerContext,
 };
 use re_viewport::ViewportUi;
 use re_viewport_blueprint::ui::add_space_view_or_container_modal_ui;
@@ -214,6 +215,10 @@ impl AppState {
             )),
         );
 
+        // The root container cannot be dragged.
+        let undraggable_items =
+            re_viewer_context::Item::Container(viewport_ui.blueprint.root_container).into();
+
         let applicable_entities_per_visualizer = space_view_class_registry
             .applicable_entities_for_visualizer_systems(&recording.store_id());
         let indicated_entities_per_visualizer =
@@ -271,6 +276,7 @@ impl AppState {
             render_ctx: Some(render_ctx),
             command_sender,
             focused_item,
+            undraggable_items: &undraggable_items,
         };
 
         // We move the time at the very start of the frame,
@@ -343,6 +349,7 @@ impl AppState {
             render_ctx: Some(render_ctx),
             command_sender,
             focused_item,
+            undraggable_items: &undraggable_items,
         };
 
         if *show_settings_ui {
@@ -509,6 +516,7 @@ impl AppState {
         //
 
         add_space_view_or_container_modal_ui(&ctx, &viewport_ui.blueprint, ui);
+        drag_and_drop_payload_cursor_ui(ui);
 
         // Process deferred layout operations and apply updates back to blueprint:
         viewport_ui.save_to_blueprint_store(&ctx, space_view_class_registry);
diff --git a/crates/viewer/re_viewer/src/ui/recordings_panel.rs b/crates/viewer/re_viewer/src/ui/recordings_panel.rs
index 49457eda91a4..1180a2a3bf99 100644
--- a/crates/viewer/re_viewer/src/ui/recordings_panel.rs
+++ b/crates/viewer/re_viewer/src/ui/recordings_panel.rs
@@ -222,7 +222,7 @@ fn app_and_its_recordings_ui(
         app_id.data_ui_recording(ctx, ui, UiLayout::Tooltip);
     });
 
-    ctx.select_hovered_on_click(&item_response, app_item);
+    ctx.select_hovered_on_click(&item_response, app_item, false);
 
     if item_response.clicked() {
         // Switch to this application:
diff --git a/crates/viewer/re_viewer_context/src/contents.rs b/crates/viewer/re_viewer_context/src/contents.rs
index a0c0d8626f42..e987f7f8df1b 100644
--- a/crates/viewer/re_viewer_context/src/contents.rs
+++ b/crates/viewer/re_viewer_context/src/contents.rs
@@ -5,7 +5,7 @@ use egui_tiles::TileId;
 use re_log_types::EntityPath;
 
 use crate::item::Item;
-use crate::{BlueprintId, BlueprintIdRegistry, ContainerId, SpaceViewId};
+use crate::{BlueprintId, BlueprintIdRegistry, ContainerId, ItemCollection, SpaceViewId};
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum Contents {
@@ -65,6 +65,14 @@ impl Contents {
     }
 }
 
+impl TryFrom<&ItemCollection> for Vec<Contents> {
+    type Error = ();
+
+    fn try_from(value: &ItemCollection) -> Result<Self, Self::Error> {
+        value.iter().map(|(item, _)| item.try_into()).collect()
+    }
+}
+
 impl TryFrom<Item> for Contents {
     type Error = ();
 
diff --git a/crates/viewer/re_viewer_context/src/drag_and_drop.rs b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
new file mode 100644
index 000000000000..b1e5e2ee67e5
--- /dev/null
+++ b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
@@ -0,0 +1,105 @@
+//! Implement a global drag-and-drop payload type that enable dragging from various parts of the UI
+//! (e.g., from the streams tree to the viewport, etc.).
+
+use std::fmt::Formatter;
+
+use crate::{Contents, ItemCollection};
+
+//TODO(ab): add more type of things we can drag, in particular entity paths
+#[derive(Debug)]
+pub enum DragAndDropPayload {
+    /// The dragged content is made only of [`Contents`].
+    Contents { contents: Vec<Contents> },
+
+    /// The dragged content is made of a collection of [`Item`]s we do know how to handle.
+    Invalid { items: crate::ItemCollection },
+}
+
+impl DragAndDropPayload {
+    pub fn from_items(selected_items: ItemCollection) -> Self {
+        if let Ok(contents) = (&selected_items).try_into() {
+            Self::Contents { contents }
+        } else {
+            Self::Invalid {
+                items: selected_items,
+            }
+        }
+    }
+}
+
+impl std::fmt::Display for DragAndDropPayload {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Contents { contents } => {
+                let (container_cnt, view_cnt) = contents.iter().fold(
+                    (0, 0),
+                    |(container_cnt, view_cnt), content| match content {
+                        Contents::Container(_) => (container_cnt + 1, view_cnt),
+                        Contents::SpaceView(_) => (container_cnt, view_cnt + 1),
+                    },
+                );
+
+                match (container_cnt, view_cnt) {
+                    (0, 0) => write!(f, "empty"), // should not happen
+                    (n, 0) => write!(f, "{n} container{}", if n > 1 { "s" } else { "" }),
+                    (0, n) => write!(f, "{n} view{}", if n > 1 { "s" } else { "" }),
+                    (container_cnt, view_cnt) => {
+                        write!(
+                            f,
+                            "{container_cnt} container{}, {view_cnt} view{}",
+                            if container_cnt > 1 { "s" } else { "" },
+                            if view_cnt > 1 { "s" } else { "" }
+                        )
+                    }
+                }
+            }
+            Self::Invalid { .. } => {
+                //TODO
+                write!(f, "invalid")
+            }
+        }
+    }
+}
+
+/// Display the currently dragged payload as a pill in the UI.
+///
+/// This should be called once per frame.
+pub fn drag_and_drop_payload_cursor_ui(ui: &mut egui::Ui) {
+    if let Some(payload) = egui::DragAndDrop::payload::<DragAndDropPayload>(ui.ctx()) {
+        if let Some(pointer_pos) = ui.ctx().pointer_interact_pos() {
+            let layer_id = egui::LayerId::new(
+                egui::Order::Tooltip,
+                egui::Id::new("drag_and_drop_payload_layer"),
+            );
+            let response = ui
+                .scope_builder(egui::UiBuilder::new().layer_id(layer_id), |ui| {
+                    //TODO: adjust look based on design
+                    egui::Frame {
+                        rounding: egui::Rounding::same(100.0), // max the rounding for a pill look
+                        fill: ui.visuals().widgets.active.text_color(),
+                        inner_margin: egui::Margin {
+                            left: 8.0,
+                            right: 8.0,
+                            top: 4.0,
+                            bottom: 3.0,
+                        },
+                        ..Default::default()
+                    }
+                    .show(ui, |ui| {
+                        ui.label(
+                            egui::RichText::new(payload.to_string()).color(ui.visuals().panel_fill),
+                        )
+                    })
+                    .inner
+                })
+                .response;
+
+            //TODO: adjust geometry
+            let delta = pointer_pos - response.rect.right_bottom();
+            ui.ctx()
+                .transform_layer_shapes(layer_id, emath::TSTransform::from_translation(delta));
+        }
+    }
+}
+
+//TODO: capture escape key to cancel drag
diff --git a/crates/viewer/re_viewer_context/src/lib.rs b/crates/viewer/re_viewer_context/src/lib.rs
index d52ce46456b5..4bd7630919d2 100644
--- a/crates/viewer/re_viewer_context/src/lib.rs
+++ b/crates/viewer/re_viewer_context/src/lib.rs
@@ -13,6 +13,7 @@ mod component_fallbacks;
 mod component_ui_registry;
 mod contents;
 mod data_result_node_or_path;
+mod drag_and_drop;
 mod file_dialog;
 mod image_info;
 mod item;
@@ -52,6 +53,7 @@ pub use self::{
     component_ui_registry::{ComponentUiRegistry, ComponentUiTypes, UiLayout},
     contents::{blueprint_id_to_tile_id, Contents, ContentsName},
     data_result_node_or_path::DataResultNodeOrPath,
+    drag_and_drop::{drag_and_drop_payload_cursor_ui, DragAndDropPayload},
     file_dialog::santitize_file_name,
     image_info::{ColormapWithRange, ImageInfo},
     item::Item,
diff --git a/crates/viewer/re_viewer_context/src/selection_state.rs b/crates/viewer/re_viewer_context/src/selection_state.rs
index 202427cac510..c4d83a532447 100644
--- a/crates/viewer/re_viewer_context/src/selection_state.rs
+++ b/crates/viewer/re_viewer_context/src/selection_state.rs
@@ -104,6 +104,15 @@ where
     }
 }
 
+impl IntoIterator for ItemCollection {
+    type Item = (Item, Option<ItemSpaceContext>);
+    type IntoIter = indexmap::map::IntoIter<Item, Option<ItemSpaceContext>>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.0.into_iter()
+    }
+}
+
 impl ItemCollection {
     /// For each item in this selection, if it refers to the first element of an instance with a
     /// single element, resolve it to a unindexed entity path.
@@ -261,6 +270,11 @@ impl ApplicationSelectionState {
         *self.selection_this_frame.lock() = items.into();
     }
 
+    /// Extend the selection with the provided items.
+    pub fn extend_selection(&self, items: impl Into<ItemCollection>) {
+        self.selection_this_frame.lock().extend(items.into());
+    }
+
     /// Returns the current selection.
     pub fn selected_items(&self) -> &ItemCollection {
         &self.selection_previous_frame
diff --git a/crates/viewer/re_viewer_context/src/space_view/view_context.rs b/crates/viewer/re_viewer_context/src/space_view/view_context.rs
index 6ed6a3e30595..a8e996fdd4b9 100644
--- a/crates/viewer/re_viewer_context/src/space_view/view_context.rs
+++ b/crates/viewer/re_viewer_context/src/space_view/view_context.rs
@@ -87,16 +87,6 @@ impl<'a> ViewContext<'a> {
         self.viewer_ctx.current_query()
     }
 
-    /// Set hover/select/focus for a given selection based on an egui response.
-    #[inline]
-    pub fn select_hovered_on_click(
-        &self,
-        response: &egui::Response,
-        selection: impl Into<crate::ItemCollection>,
-    ) {
-        self.viewer_ctx.select_hovered_on_click(response, selection);
-    }
-
     #[inline]
     pub fn lookup_query_result(&self, id: SpaceViewId) -> &DataQueryResult {
         self.viewer_ctx.lookup_query_result(id)
diff --git a/crates/viewer/re_viewer_context/src/test_context.rs b/crates/viewer/re_viewer_context/src/test_context.rs
index c2c75e74babb..7485309683c1 100644
--- a/crates/viewer/re_viewer_context/src/test_context.rs
+++ b/crates/viewer/re_viewer_context/src/test_context.rs
@@ -90,6 +90,8 @@ impl TestContext {
             hub: &Default::default(),
         };
 
+        let undraggable_items = Default::default();
+
         let ctx = ViewerContext {
             app_options: &Default::default(),
             cache: &Default::default(),
@@ -108,6 +110,7 @@ impl TestContext {
             render_ctx: None,
             command_sender: &self.command_sender,
             focused_item: &None,
+            undraggable_items: &undraggable_items,
         };
 
         func(&ctx);
diff --git a/crates/viewer/re_viewer_context/src/viewer_context.rs b/crates/viewer/re_viewer_context/src/viewer_context.rs
index 5e8cd4f8ce07..e40716c1a020 100644
--- a/crates/viewer/re_viewer_context/src/viewer_context.rs
+++ b/crates/viewer/re_viewer_context/src/viewer_context.rs
@@ -5,6 +5,7 @@ use re_chunk_store::LatestAtQuery;
 use re_entity_db::entity_db::EntityDb;
 use re_query::StorageEngineReadGuard;
 
+use crate::drag_and_drop::DragAndDropPayload;
 use crate::{
     query_context::DataQueryResult, AppOptions, ApplicableEntities, ApplicationSelectionState,
     Caches, CommandSender, ComponentUiRegistry, IndicatedEntities, ItemCollection, PerVisualizer,
@@ -79,6 +80,9 @@ pub struct ViewerContext<'a> {
     /// The focused item is cleared every frame, but views may react with side-effects
     /// that last several frames.
     pub focused_item: &'a Option<crate::Item>,
+
+    /// If a selection contains any `undraggable_items`, it may not be dragged.
+    pub undraggable_items: &'a ItemCollection,
 }
 
 impl ViewerContext<'_> {
@@ -131,11 +135,13 @@ impl ViewerContext<'_> {
         self.rec_cfg.time_ctrl.read().current_query()
     }
 
+    //TODO: rename this method
     /// Set hover/select/focus for a given selection based on an egui response.
     pub fn select_hovered_on_click(
         &self,
         response: &egui::Response,
         selection: impl Into<ItemCollection>,
+        can_be_dragged: bool,
     ) {
         re_tracing::profile_function!();
 
@@ -146,14 +152,40 @@ impl ViewerContext<'_> {
             selection_state.set_hovered(selection.clone());
         }
 
-        if response.double_clicked() {
+        if can_be_dragged && response.drag_started() {
+            let mut selected_items = selection_state.selected_items().clone();
+            let is_already_selected = selection
+                .iter()
+                .all(|(item, _)| selected_items.contains_item(item));
+            if !is_already_selected {
+                if response.ctx.input(|i| i.modifiers.command) {
+                    selected_items.extend(selection);
+                } else {
+                    selected_items = selection;
+                }
+                selection_state.set_selection(selected_items.clone());
+            }
+
+            let is_selection_draggable = self
+                .undraggable_items
+                .iter_items()
+                .all(|item| !selected_items.contains_item(item));
+
+            let payload = if is_selection_draggable {
+                DragAndDropPayload::from_items(selected_items)
+            } else {
+                DragAndDropPayload::Invalid {
+                    items: selected_items,
+                }
+            };
+
+            egui::DragAndDrop::set_payload(&response.ctx, payload);
+        } else if response.double_clicked() {
             if let Some(item) = selection.first_item() {
                 self.command_sender
                     .send_system(crate::SystemCommand::SetFocus(item.clone()));
             }
-        }
-
-        if response.clicked() {
+        } else if response.clicked() {
             if response.ctx.input(|i| i.modifiers.command) {
                 selection_state.toggle_selection(selection);
             } else {
diff --git a/crates/viewer/re_viewport/src/viewport_ui.rs b/crates/viewer/re_viewport/src/viewport_ui.rs
index ff03ad6cc05a..37104f81f024 100644
--- a/crates/viewer/re_viewport/src/viewport_ui.rs
+++ b/crates/viewer/re_viewport/src/viewport_ui.rs
@@ -597,7 +597,7 @@ impl<'a> egui_tiles::Behavior<SpaceViewId> for TilesDelegate<'a, '_> {
                 &response,
                 SelectionUpdateBehavior::OverrideSelection,
             );
-            self.ctx.select_hovered_on_click(&response, item);
+            self.ctx.select_hovered_on_click(&response, item, false);
         }
 
         response
diff --git a/examples/rust/custom_space_view/src/color_coordinates_space_view.rs b/examples/rust/custom_space_view/src/color_coordinates_space_view.rs
index 9bcec0ca9ec1..7b78fbc17b55 100644
--- a/examples/rust/custom_space_view/src/color_coordinates_space_view.rs
+++ b/examples/rust/custom_space_view/src/color_coordinates_space_view.rs
@@ -279,7 +279,11 @@ fn color_space_ui(
                     ctx.recording(),
                 );
             });
-            ctx.select_hovered_on_click(&interact, Item::DataResult(query.space_view_id, instance));
+            ctx.select_hovered_on_click(
+                &interact,
+                Item::DataResult(query.space_view_id, instance),
+                false,
+            );
         }
     }
 

From 9a92effac550a3503b527e61af9243038b202e8a Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Thu, 5 Dec 2024 15:20:25 +0100
Subject: [PATCH 02/14] post rebase

---
 Cargo.lock                                            | 1 +
 crates/build/re_types_builder/src/codegen/rust/api.rs | 2 +-
 crates/viewer/re_space_view_graph/src/ui/draw.rs      | 3 ++-
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 5f7eabcdb372..227a9ebb4ad8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6587,6 +6587,7 @@ dependencies = [
  "egui_extras",
  "egui_kittest",
  "egui_tiles",
+ "nohash-hasher",
  "once_cell",
  "parking_lot",
  "rand",
diff --git a/crates/build/re_types_builder/src/codegen/rust/api.rs b/crates/build/re_types_builder/src/codegen/rust/api.rs
index 90b01d69e1a2..0f5ba7c5f8a4 100644
--- a/crates/build/re_types_builder/src/codegen/rust/api.rs
+++ b/crates/build/re_types_builder/src/codegen/rust/api.rs
@@ -1085,7 +1085,7 @@ fn quote_trait_impls_for_archetype(obj: &Object) -> TokenStream {
 
     let quoted_field_names = obj
         .fields
-        .iter()
+        .ite
         .map(|field| format_ident!("{}", field.name))
         .collect::<Vec<_>>();
 
diff --git a/crates/viewer/re_space_view_graph/src/ui/draw.rs b/crates/viewer/re_space_view_graph/src/ui/draw.rs
index 24e393687677..e0f132cf6e4f 100644
--- a/crates/viewer/re_space_view_graph/src/ui/draw.rs
+++ b/crates/viewer/re_space_view_graph/src/ui/draw.rs
@@ -289,7 +289,8 @@ pub fn draw_graph(
                     InstancePath::instance(entity_path.clone(), instance.instance_index);
                 ctx.select_hovered_on_click(
                     &response,
-                    Item::DataResult(query.space_view_id, instance_path.clone(), false),
+                    Item::DataResult(query.space_view_id, instance_path.clone()),
+                    false,
                 );
 
                 response = response.on_hover_ui_at_pointer(|ui| {

From ded726527a345cb77396c100e9e671b391994341 Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Thu, 5 Dec 2024 19:14:23 +0100
Subject: [PATCH 03/14] Better display of the drag item

---
 Cargo.lock                                    |   1 -
 .../re_types_builder/src/codegen/rust/api.rs  |   2 +-
 .../viewer/re_ui/data/icons/dnd_add_new.png   | Bin 0 -> 430 bytes
 .../re_ui/data/icons/dnd_add_to_existing.png  | Bin 0 -> 557 bytes
 .../re_ui/data/icons/dnd_cannot_use.png       | Bin 0 -> 685 bytes
 crates/viewer/re_ui/data/icons/dnd_move.png   | Bin 0 -> 450 bytes
 crates/viewer/re_ui/src/design_tokens.rs      |   2 +-
 crates/viewer/re_ui/src/icons.rs              |   6 +
 crates/viewer/re_ui/src/ui_ext.rs             |  15 ++
 .../re_viewer_context/src/drag_and_drop.rs    | 162 +++++++++++++-----
 10 files changed, 139 insertions(+), 49 deletions(-)
 create mode 100644 crates/viewer/re_ui/data/icons/dnd_add_new.png
 create mode 100644 crates/viewer/re_ui/data/icons/dnd_add_to_existing.png
 create mode 100644 crates/viewer/re_ui/data/icons/dnd_cannot_use.png
 create mode 100644 crates/viewer/re_ui/data/icons/dnd_move.png

diff --git a/Cargo.lock b/Cargo.lock
index 227a9ebb4ad8..5f7eabcdb372 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6587,7 +6587,6 @@ dependencies = [
  "egui_extras",
  "egui_kittest",
  "egui_tiles",
- "nohash-hasher",
  "once_cell",
  "parking_lot",
  "rand",
diff --git a/crates/build/re_types_builder/src/codegen/rust/api.rs b/crates/build/re_types_builder/src/codegen/rust/api.rs
index 0f5ba7c5f8a4..90b01d69e1a2 100644
--- a/crates/build/re_types_builder/src/codegen/rust/api.rs
+++ b/crates/build/re_types_builder/src/codegen/rust/api.rs
@@ -1085,7 +1085,7 @@ fn quote_trait_impls_for_archetype(obj: &Object) -> TokenStream {
 
     let quoted_field_names = obj
         .fields
-        .ite
+        .iter()
         .map(|field| format_ident!("{}", field.name))
         .collect::<Vec<_>>();
 
diff --git a/crates/viewer/re_ui/data/icons/dnd_add_new.png b/crates/viewer/re_ui/data/icons/dnd_add_new.png
new file mode 100644
index 0000000000000000000000000000000000000000..ae2caea2210872e2935c9992651373d10e150ccf
GIT binary patch
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Y1n<RWdj>>CaR2}S07*qoM6N<$f?Yea>;M1&

literal 0
HcmV?d00001

diff --git a/crates/viewer/re_ui/data/icons/dnd_add_to_existing.png b/crates/viewer/re_ui/data/icons/dnd_add_to_existing.png
new file mode 100644
index 0000000000000000000000000000000000000000..815fd872b22a319f96b4500aefb8c5b1b7f75879
GIT binary patch
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literal 0
HcmV?d00001

diff --git a/crates/viewer/re_ui/data/icons/dnd_cannot_use.png b/crates/viewer/re_ui/data/icons/dnd_cannot_use.png
new file mode 100644
index 0000000000000000000000000000000000000000..db1ba198f7441a6b9517e5e662285243f219aefb
GIT binary patch
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literal 0
HcmV?d00001

diff --git a/crates/viewer/re_ui/data/icons/dnd_move.png b/crates/viewer/re_ui/data/icons/dnd_move.png
new file mode 100644
index 0000000000000000000000000000000000000000..3eb30f42e8ce9179b3e1e76f78092d0e91e6f3b8
GIT binary patch
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literal 0
HcmV?d00001

diff --git a/crates/viewer/re_ui/src/design_tokens.rs b/crates/viewer/re_ui/src/design_tokens.rs
index de05e49c0e87..50acbbd2e7e4 100644
--- a/crates/viewer/re_ui/src/design_tokens.rs
+++ b/crates/viewer/re_ui/src/design_tokens.rs
@@ -247,7 +247,7 @@ impl DesignTokens {
 
         egui_style.visuals.image_loading_spinners = false;
 
-        //TODO(ab): use ColorToken!
+        //TODO(#8333): use ColorToken!
         egui_style.visuals.error_fg_color = egui::Color32::from_rgb(0xAB, 0x01, 0x16);
         egui_style.visuals.warn_fg_color = egui::Color32::from_rgb(0xFF, 0x7A, 0x0C);
 
diff --git a/crates/viewer/re_ui/src/icons.rs b/crates/viewer/re_ui/src/icons.rs
index 8ec9dcdab2fc..aa791909fc93 100644
--- a/crates/viewer/re_ui/src/icons.rs
+++ b/crates/viewer/re_ui/src/icons.rs
@@ -119,5 +119,11 @@ pub const GITHUB: Icon = icon_from_path!("../data/icons/github.png");
 
 pub const VIDEO_ERROR: Icon = icon_from_path!("../data/icons/video_error.png");
 
+// drag and drop icons
+pub const DND_ADD_NEW: Icon = icon_from_path!("../data/icons/dnd_add_new.png");
+pub const DND_ADD_TO_EXISTING: Icon = icon_from_path!("../data/icons/dnd_add_to_existing.png");
+pub const DND_CANNOT_USE: Icon = icon_from_path!("../data/icons/dnd_cannot_use.png");
+pub const DND_MOVE: Icon = icon_from_path!("../data/icons/dnd_move.png");
+
 /// `>`
 pub const BREADCRUMBS_SEPARATOR: Icon = icon_from_path!("../data/icons/breadcrumbs_separator.png");
diff --git a/crates/viewer/re_ui/src/ui_ext.rs b/crates/viewer/re_ui/src/ui_ext.rs
index d791d2edb20f..210814ac99c6 100644
--- a/crates/viewer/re_ui/src/ui_ext.rs
+++ b/crates/viewer/re_ui/src/ui_ext.rs
@@ -131,6 +131,21 @@ pub trait UiExt {
         )
     }
 
+    /// Adds a non-interactive, optionally tinted small icon.
+    ///
+    /// Uses [`DesignTokens::small_icon_size`]. Returns the rect where the icon was painted.
+    fn small_icon(&mut self, icon: &Icon, tint: Option<egui::Color32>) -> egui::Rect {
+        let ui = self.ui_mut();
+        let (_, rect) = ui.allocate_space(DesignTokens::small_icon_size());
+        let mut image = icon.as_image();
+        if let Some(tint) = tint {
+            image = image.tint(tint);
+        }
+        image.paint_at(ui, rect);
+
+        rect
+    }
+
     fn medium_icon_toggle_button(&mut self, icon: &Icon, selected: &mut bool) -> egui::Response {
         let size_points = egui::Vec2::splat(16.0); // TODO(emilk): get from design tokens
 
diff --git a/crates/viewer/re_viewer_context/src/drag_and_drop.rs b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
index b1e5e2ee67e5..1feb9c73f617 100644
--- a/crates/viewer/re_viewer_context/src/drag_and_drop.rs
+++ b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
@@ -3,7 +3,15 @@
 
 use std::fmt::Formatter;
 
-use crate::{Contents, ItemCollection};
+use itertools::Itertools;
+
+use re_ui::{
+    ColorToken, Hue,
+    Shade::{S325, S375},
+    UiExt,
+};
+
+use crate::{Contents, Item, ItemCollection};
 
 //TODO(ab): add more type of things we can drag, in particular entity paths
 #[derive(Debug)]
@@ -30,33 +38,16 @@ impl DragAndDropPayload {
 impl std::fmt::Display for DragAndDropPayload {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         match self {
-            Self::Contents { contents } => {
-                let (container_cnt, view_cnt) = contents.iter().fold(
-                    (0, 0),
-                    |(container_cnt, view_cnt), content| match content {
-                        Contents::Container(_) => (container_cnt + 1, view_cnt),
-                        Contents::SpaceView(_) => (container_cnt, view_cnt + 1),
-                    },
-                );
-
-                match (container_cnt, view_cnt) {
-                    (0, 0) => write!(f, "empty"), // should not happen
-                    (n, 0) => write!(f, "{n} container{}", if n > 1 { "s" } else { "" }),
-                    (0, n) => write!(f, "{n} view{}", if n > 1 { "s" } else { "" }),
-                    (container_cnt, view_cnt) => {
-                        write!(
-                            f,
-                            "{container_cnt} container{}, {view_cnt} view{}",
-                            if container_cnt > 1 { "s" } else { "" },
-                            if view_cnt > 1 { "s" } else { "" }
-                        )
-                    }
-                }
-            }
-            Self::Invalid { .. } => {
-                //TODO
-                write!(f, "invalid")
-            }
+            Self::Contents { contents } => items_to_string(
+                contents
+                    .iter()
+                    .map(|content| content.as_item())
+                    .collect_vec()
+                    .iter(),
+            )
+            .fmt(f),
+
+            Self::Invalid { items } => items_to_string(items.iter_items()).fmt(f),
         }
     }
 }
@@ -67,34 +58,35 @@ impl std::fmt::Display for DragAndDropPayload {
 pub fn drag_and_drop_payload_cursor_ui(ui: &mut egui::Ui) {
     if let Some(payload) = egui::DragAndDrop::payload::<DragAndDropPayload>(ui.ctx()) {
         if let Some(pointer_pos) = ui.ctx().pointer_interact_pos() {
+            let icon = match payload.as_ref() {
+                DragAndDropPayload::Contents { .. } => &re_ui::icons::DND_MOVE,
+                DragAndDropPayload::Invalid { .. } => &re_ui::icons::DND_CANNOT_USE,
+            };
+
             let layer_id = egui::LayerId::new(
                 egui::Order::Tooltip,
                 egui::Id::new("drag_and_drop_payload_layer"),
             );
             let response = ui
                 .scope_builder(egui::UiBuilder::new().layer_id(layer_id), |ui| {
-                    //TODO: adjust look based on design
-                    egui::Frame {
-                        rounding: egui::Rounding::same(100.0), // max the rounding for a pill look
-                        fill: ui.visuals().widgets.active.text_color(),
-                        inner_margin: egui::Margin {
-                            left: 8.0,
-                            right: 8.0,
-                            top: 4.0,
-                            bottom: 3.0,
-                        },
-                        ..Default::default()
-                    }
+                    drag_pill_frame(matches!(
+                        payload.as_ref(),
+                        &DragAndDropPayload::Invalid { .. }
+                    ))
                     .show(ui, |ui| {
-                        ui.label(
-                            egui::RichText::new(payload.to_string()).color(ui.visuals().panel_fill),
-                        )
+                        let text_color = ui.visuals().widgets.inactive.text_color();
+
+                        ui.horizontal(|ui| {
+                            ui.spacing_mut().item_spacing.x = 2.0;
+
+                            ui.small_icon(icon, Some(text_color));
+                            ui.label(egui::RichText::new(payload.to_string()).color(text_color));
+                        });
                     })
-                    .inner
+                    .response
                 })
                 .response;
 
-            //TODO: adjust geometry
             let delta = pointer_pos - response.rect.right_bottom();
             ui.ctx()
                 .transform_layer_shapes(layer_id, emath::TSTransform::from_translation(delta));
@@ -102,4 +94,82 @@ pub fn drag_and_drop_payload_cursor_ui(ui: &mut egui::Ui) {
     }
 }
 
-//TODO: capture escape key to cancel drag
+fn drag_pill_frame(error_state: bool) -> egui::Frame {
+    let hue = if error_state { Hue::Red } else { Hue::Blue };
+
+    egui::Frame {
+        fill: re_ui::design_tokens().color(ColorToken::new(hue, S325)),
+        stroke: egui::Stroke::new(
+            1.0,
+            re_ui::design_tokens().color(ColorToken::new(hue, S375)),
+        ),
+        rounding: (2.0).into(),
+        inner_margin: egui::Margin {
+            left: 6.0,
+            right: 9.0,
+            top: 5.0,
+            bottom: 4.0,
+        },
+        ..Default::default()
+    }
+}
+
+fn items_to_string<'a>(items: impl Iterator<Item = &'a Item>) -> String {
+    let mut container_cnt = 0u32;
+    let mut view_cnt = 0u32;
+    let mut app_cnt = 0u32;
+    let mut data_source_cnt = 0u32;
+    let mut store_cnt = 0u32;
+    let mut instance_cnt = 0u32;
+    let mut component_cnt = 0u32;
+
+    for item in items {
+        match item {
+            Item::Container(_) => container_cnt += 1,
+            Item::SpaceView(_) => view_cnt += 1,
+            Item::AppId(_) => app_cnt += 1,
+            Item::DataSource(_) => data_source_cnt += 1,
+            Item::StoreId(_) => store_cnt += 1,
+            Item::InstancePath(_) => instance_cnt += 1,
+            Item::ComponentPath(_) => component_cnt += 1,
+            Item::DataResult(_, _) => instance_cnt += 1,
+        }
+    }
+
+    let counts = [
+        &container_cnt,
+        &view_cnt,
+        &app_cnt,
+        &data_source_cnt,
+        &store_cnt,
+        &instance_cnt,
+        &component_cnt,
+    ];
+
+    let names = [
+        "container",
+        "view",
+        "app",
+        "data source",
+        "store",
+        "instance",
+        "component",
+    ];
+
+    counts
+        .iter()
+        .zip(names.iter())
+        .filter_map(|(&&cnt, &name)| {
+            if cnt > 0 {
+                Some(format!(
+                    "{} {}{}",
+                    cnt,
+                    name,
+                    if cnt > 1 { "s" } else { "" }
+                ))
+            } else {
+                None
+            }
+        })
+        .join(", ")
+}

From 0f9b14e2d94834988856d9ddf2d61b324cc924dc Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Fri, 6 Dec 2024 10:33:23 +0100
Subject: [PATCH 04/14] Renamed `select_hovered_on_click` to
 `handle_select_hover_drag_interactions`

---
 crates/viewer/re_blueprint_tree/src/blueprint_tree.rs |  8 ++++----
 crates/viewer/re_data_ui/src/instance_path.rs         |  2 +-
 crates/viewer/re_data_ui/src/item_ui.rs               |  2 +-
 .../viewer/re_selection_panel/src/selection_panel.rs  |  4 ++--
 .../re_space_view_bar_chart/src/space_view_class.rs   |  2 +-
 .../re_space_view_dataframe/src/dataframe_ui.rs       |  5 +++--
 crates/viewer/re_space_view_graph/src/ui/draw.rs      |  4 ++--
 crates/viewer/re_space_view_map/src/map_space_view.rs |  2 +-
 crates/viewer/re_space_view_spatial/src/picking_ui.rs |  2 +-
 .../re_space_view_time_series/src/space_view_class.rs |  2 +-
 crates/viewer/re_time_panel/src/lib.rs                |  4 ++--
 crates/viewer/re_viewer/src/ui/recordings_panel.rs    |  2 +-
 crates/viewer/re_viewer_context/src/viewer_context.rs | 11 ++++++-----
 crates/viewer/re_viewport/src/viewport_ui.rs          |  3 ++-
 .../src/color_coordinates_space_view.rs               |  2 +-
 15 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs b/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
index 62efc89ede41..8554f490dc4b 100644
--- a/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
+++ b/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
@@ -189,7 +189,7 @@ impl BlueprintTree {
             SelectionUpdateBehavior::UseSelection,
         );
         self.scroll_to_me_if_needed(ui, &item, &item_response);
-        ctx.select_hovered_on_click(&item_response, item, true);
+        ctx.handle_select_hover_drag_interactions(&item_response, item, true);
 
         self.handle_root_container_drag_and_drop_interaction(
             viewport,
@@ -270,7 +270,7 @@ impl BlueprintTree {
             SelectionUpdateBehavior::UseSelection,
         );
         self.scroll_to_me_if_needed(ui, &item, &response);
-        ctx.select_hovered_on_click(&response, item, true);
+        ctx.handle_select_hover_drag_interactions(&response, item, true);
 
         viewport.set_content_visibility(ctx, &content, visible);
 
@@ -409,7 +409,7 @@ impl BlueprintTree {
             SelectionUpdateBehavior::UseSelection,
         );
         self.scroll_to_me_if_needed(ui, &item, &response);
-        ctx.select_hovered_on_click(&response, item, true);
+        ctx.handle_select_hover_drag_interactions(&response, item, true);
 
         let content = Contents::SpaceView(*space_view_id);
 
@@ -602,7 +602,7 @@ impl BlueprintTree {
             SelectionUpdateBehavior::UseSelection,
         );
         self.scroll_to_me_if_needed(ui, &item, &response);
-        ctx.select_hovered_on_click(&response, item, true);
+        ctx.handle_select_hover_drag_interactions(&response, item, true);
     }
 
     /// Add a button to trigger the addition of a new space view or container.
diff --git a/crates/viewer/re_data_ui/src/instance_path.rs b/crates/viewer/re_data_ui/src/instance_path.rs
index 887b02a4df5f..2b294084b2f9 100644
--- a/crates/viewer/re_data_ui/src/instance_path.rs
+++ b/crates/viewer/re_data_ui/src/instance_path.rs
@@ -243,7 +243,7 @@ fn component_list_ui(
             });
 
             if interactive {
-                ctx.select_hovered_on_click(&response, item, false);
+                ctx.handle_select_hover_drag_interactions(&response, item, false);
             }
         }
     });
diff --git a/crates/viewer/re_data_ui/src/item_ui.rs b/crates/viewer/re_data_ui/src/item_ui.rs
index 12625645bb3c..b68e2753f3d3 100644
--- a/crates/viewer/re_data_ui/src/item_ui.rs
+++ b/crates/viewer/re_data_ui/src/item_ui.rs
@@ -596,7 +596,7 @@ pub fn cursor_interact_with_selectable(
     let is_item_hovered =
         ctx.selection_state().highlight_for_ui_element(&item) == HoverHighlight::Hovered;
 
-    ctx.select_hovered_on_click(&response, item, false);
+    ctx.handle_select_hover_drag_interactions(&response, item, false);
     // TODO(andreas): How to deal with shift click for selecting ranges?
 
     if is_item_hovered {
diff --git a/crates/viewer/re_selection_panel/src/selection_panel.rs b/crates/viewer/re_selection_panel/src/selection_panel.rs
index aede775a7118..0729cc5e103c 100644
--- a/crates/viewer/re_selection_panel/src/selection_panel.rs
+++ b/crates/viewer/re_selection_panel/src/selection_panel.rs
@@ -656,7 +656,7 @@ fn list_existing_data_blueprints(
 
                 // We don't use item_ui::cursor_interact_with_selectable here because the forced
                 // hover background is distracting and not useful.
-                ctx.select_hovered_on_click(&response, item, false);
+                ctx.handle_select_hover_drag_interactions(&response, item, false);
             }
         }
     }
@@ -907,7 +907,7 @@ fn show_list_item_for_container_child(
         &response,
         SelectionUpdateBehavior::Ignore,
     );
-    ctx.select_hovered_on_click(&response, item, false);
+    ctx.handle_select_hover_drag_interactions(&response, item, false);
 
     if remove_contents {
         viewport.mark_user_interaction(ctx);
diff --git a/crates/viewer/re_space_view_bar_chart/src/space_view_class.rs b/crates/viewer/re_space_view_bar_chart/src/space_view_class.rs
index 729d23ac4e4f..139953eddc32 100644
--- a/crates/viewer/re_space_view_bar_chart/src/space_view_class.rs
+++ b/crates/viewer/re_space_view_bar_chart/src/space_view_class.rs
@@ -242,7 +242,7 @@ Display a 1D tensor as a bar chart.
             if let Some(entity_path) = hovered_plot_item
                 .and_then(|hovered_plot_item| plot_item_id_to_entity_path.get(&hovered_plot_item))
             {
-                ctx.select_hovered_on_click(
+                ctx.handle_select_hover_drag_interactions(
                     &response,
                     re_viewer_context::Item::DataResult(
                         query.space_view_id,
diff --git a/crates/viewer/re_space_view_dataframe/src/dataframe_ui.rs b/crates/viewer/re_space_view_dataframe/src/dataframe_ui.rs
index 88f1f4d849a0..a25f1d77ed11 100644
--- a/crates/viewer/re_space_view_dataframe/src/dataframe_ui.rs
+++ b/crates/viewer/re_space_view_dataframe/src/dataframe_ui.rs
@@ -261,7 +261,8 @@ impl egui_table::TableDelegate for DataframeTableDelegate<'_> {
                             egui::Rect::from_min_size(pos, size),
                             egui::SelectableLabel::new(is_selected, galley),
                         );
-                        self.ctx.select_hovered_on_click(&response, item, false);
+                        self.ctx
+                            .handle_select_hover_drag_interactions(&response, item, false);
 
                         // TODO(emilk): expand column(s) to make sure the text fits (requires egui_table fix).
                     }
@@ -319,7 +320,7 @@ impl egui_table::TableDelegate for DataframeTableDelegate<'_> {
                                 }
                             }
                             ColumnDescriptor::Component(component_column_descriptor) => {
-                                self.ctx.select_hovered_on_click(
+                                self.ctx.handle_select_hover_drag_interactions(
                                     &response,
                                     re_viewer_context::Item::ComponentPath(
                                         component_column_descriptor.component_path(),
diff --git a/crates/viewer/re_space_view_graph/src/ui/draw.rs b/crates/viewer/re_space_view_graph/src/ui/draw.rs
index e0f132cf6e4f..8cf368411e33 100644
--- a/crates/viewer/re_space_view_graph/src/ui/draw.rs
+++ b/crates/viewer/re_space_view_graph/src/ui/draw.rs
@@ -287,7 +287,7 @@ pub fn draw_graph(
 
                 let instance_path =
                     InstancePath::instance(entity_path.clone(), instance.instance_index);
-                ctx.select_hovered_on_click(
+                ctx.handle_select_hover_drag_interactions(
                     &response,
                     Item::DataResult(query.space_view_id, instance_path.clone()),
                     false,
@@ -335,7 +335,7 @@ pub fn draw_graph(
             let resp = draw_entity_rect(ui, *rect, entity_path, &query.highlights);
             current_rect = current_rect.union(resp.rect);
             let instance_path = InstancePath::entity_all(entity_path.clone());
-            ctx.select_hovered_on_click(
+            ctx.handle_select_hover_drag_interactions(
                 &resp,
                 Item::DataResult(query.space_view_id, instance_path),
                 false,
diff --git a/crates/viewer/re_space_view_map/src/map_space_view.rs b/crates/viewer/re_space_view_map/src/map_space_view.rs
index 481b55748324..e84ddf2a5712 100644
--- a/crates/viewer/re_space_view_map/src/map_space_view.rs
+++ b/crates/viewer/re_space_view_map/src/map_space_view.rs
@@ -481,7 +481,7 @@ fn handle_ui_interactions(
             });
         });
 
-        ctx.select_hovered_on_click(
+        ctx.handle_select_hover_drag_interactions(
             &map_response,
             Item::DataResult(query.space_view_id, instance_path.clone()),
             false,
diff --git a/crates/viewer/re_space_view_spatial/src/picking_ui.rs b/crates/viewer/re_space_view_spatial/src/picking_ui.rs
index e9962df58a26..62a168f6f0aa 100644
--- a/crates/viewer/re_space_view_spatial/src/picking_ui.rs
+++ b/crates/viewer/re_space_view_spatial/src/picking_ui.rs
@@ -209,7 +209,7 @@ pub fn picking(
         });
     };
 
-    ctx.select_hovered_on_click(&response, hovered_items.into_iter(), false);
+    ctx.handle_select_hover_drag_interactions(&response, hovered_items.into_iter(), false);
 
     Ok(response)
 }
diff --git a/crates/viewer/re_space_view_time_series/src/space_view_class.rs b/crates/viewer/re_space_view_time_series/src/space_view_class.rs
index c01ab1ece767..40f6747bcc28 100644
--- a/crates/viewer/re_space_view_time_series/src/space_view_class.rs
+++ b/crates/viewer/re_space_view_time_series/src/space_view_class.rs
@@ -536,7 +536,7 @@ Display time series data in a plot.
                     }
                 })
             {
-                ctx.select_hovered_on_click(&response, hovered, false);
+                ctx.handle_select_hover_drag_interactions(&response, hovered, false);
             }
         }
 
diff --git a/crates/viewer/re_time_panel/src/lib.rs b/crates/viewer/re_time_panel/src/lib.rs
index 39dd59764cdb..ec4c9bf5b170 100644
--- a/crates/viewer/re_time_panel/src/lib.rs
+++ b/crates/viewer/re_time_panel/src/lib.rs
@@ -726,7 +726,7 @@ impl TimePanel {
             &response,
             SelectionUpdateBehavior::UseSelection,
         );
-        ctx.select_hovered_on_click(&response, item.to_item(), false);
+        ctx.handle_select_hover_drag_interactions(&response, item.to_item(), false);
 
         let is_closed = body_response.is_none();
         let response_rect = response.rect;
@@ -854,7 +854,7 @@ impl TimePanel {
                     &response,
                     SelectionUpdateBehavior::UseSelection,
                 );
-                ctx.select_hovered_on_click(&response, item.to_item(), false);
+                ctx.handle_select_hover_drag_interactions(&response, item.to_item(), false);
 
                 let response_rect = response.rect;
 
diff --git a/crates/viewer/re_viewer/src/ui/recordings_panel.rs b/crates/viewer/re_viewer/src/ui/recordings_panel.rs
index 1180a2a3bf99..378d0c34f9fa 100644
--- a/crates/viewer/re_viewer/src/ui/recordings_panel.rs
+++ b/crates/viewer/re_viewer/src/ui/recordings_panel.rs
@@ -222,7 +222,7 @@ fn app_and_its_recordings_ui(
         app_id.data_ui_recording(ctx, ui, UiLayout::Tooltip);
     });
 
-    ctx.select_hovered_on_click(&item_response, app_item, false);
+    ctx.handle_select_hover_drag_interactions(&item_response, app_item, false);
 
     if item_response.clicked() {
         // Switch to this application:
diff --git a/crates/viewer/re_viewer_context/src/viewer_context.rs b/crates/viewer/re_viewer_context/src/viewer_context.rs
index e40716c1a020..72748e05fb6c 100644
--- a/crates/viewer/re_viewer_context/src/viewer_context.rs
+++ b/crates/viewer/re_viewer_context/src/viewer_context.rs
@@ -135,13 +135,14 @@ impl ViewerContext<'_> {
         self.rec_cfg.time_ctrl.read().current_query()
     }
 
-    //TODO: rename this method
-    /// Set hover/select/focus for a given selection based on an egui response.
-    pub fn select_hovered_on_click(
+    /// Consistently handle the selection, hover, drag start interactions for a given set of items.
+    ///
+    /// The drag start interaction is optional and controlled by the `draggable` parameter.
+    pub fn handle_select_hover_drag_interactions(
         &self,
         response: &egui::Response,
         selection: impl Into<ItemCollection>,
-        can_be_dragged: bool,
+        draggable: bool,
     ) {
         re_tracing::profile_function!();
 
@@ -152,7 +153,7 @@ impl ViewerContext<'_> {
             selection_state.set_hovered(selection.clone());
         }
 
-        if can_be_dragged && response.drag_started() {
+        if draggable && response.drag_started() {
             let mut selected_items = selection_state.selected_items().clone();
             let is_already_selected = selection
                 .iter()
diff --git a/crates/viewer/re_viewport/src/viewport_ui.rs b/crates/viewer/re_viewport/src/viewport_ui.rs
index 37104f81f024..d4253995ff2d 100644
--- a/crates/viewer/re_viewport/src/viewport_ui.rs
+++ b/crates/viewer/re_viewport/src/viewport_ui.rs
@@ -597,7 +597,8 @@ impl<'a> egui_tiles::Behavior<SpaceViewId> for TilesDelegate<'a, '_> {
                 &response,
                 SelectionUpdateBehavior::OverrideSelection,
             );
-            self.ctx.select_hovered_on_click(&response, item, false);
+            self.ctx
+                .handle_select_hover_drag_interactions(&response, item, false);
         }
 
         response
diff --git a/examples/rust/custom_space_view/src/color_coordinates_space_view.rs b/examples/rust/custom_space_view/src/color_coordinates_space_view.rs
index 7b78fbc17b55..11641c56c7cf 100644
--- a/examples/rust/custom_space_view/src/color_coordinates_space_view.rs
+++ b/examples/rust/custom_space_view/src/color_coordinates_space_view.rs
@@ -279,7 +279,7 @@ fn color_space_ui(
                     ctx.recording(),
                 );
             });
-            ctx.select_hovered_on_click(
+            ctx.handle_select_hover_drag_interactions(
                 &interact,
                 Item::DataResult(query.space_view_id, instance),
                 false,

From 7b15fed3d6b47d6ac5606ddd95eb29af8739ef0b Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Fri, 6 Dec 2024 15:22:34 +0100
Subject: [PATCH 05/14] 70% opacity for the bluepill

---
 crates/viewer/re_viewer_context/src/drag_and_drop.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/crates/viewer/re_viewer_context/src/drag_and_drop.rs b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
index 1feb9c73f617..5ec33e27f1f6 100644
--- a/crates/viewer/re_viewer_context/src/drag_and_drop.rs
+++ b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
@@ -69,6 +69,8 @@ pub fn drag_and_drop_payload_cursor_ui(ui: &mut egui::Ui) {
             );
             let response = ui
                 .scope_builder(egui::UiBuilder::new().layer_id(layer_id), |ui| {
+                    ui.set_opacity(0.7);
+
                     drag_pill_frame(matches!(
                         payload.as_ref(),
                         &DragAndDropPayload::Invalid { .. }

From 1c09ca9960da79727c529d4d9b8f569650038d41 Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Fri, 6 Dec 2024 16:53:37 +0100
Subject: [PATCH 06/14] post rebase

---
 crates/viewer/re_viewer_context/src/drag_and_drop.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/viewer/re_viewer_context/src/drag_and_drop.rs b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
index 5ec33e27f1f6..3aa2546bdcbd 100644
--- a/crates/viewer/re_viewer_context/src/drag_and_drop.rs
+++ b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
@@ -7,7 +7,7 @@ use itertools::Itertools;
 
 use re_ui::{
     ColorToken, Hue,
-    Shade::{S325, S375},
+    Scale::{S325, S375},
     UiExt,
 };
 

From 306ff860aa3492d3719fbfdb38ee157e716ea29a Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Mon, 9 Dec 2024 11:02:50 +0100
Subject: [PATCH 07/14] Properly deal with entity vs. instance

---
 .../re_viewer_context/src/drag_and_drop.rs    | 31 ++++++++++++-------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/crates/viewer/re_viewer_context/src/drag_and_drop.rs b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
index 3aa2546bdcbd..41ce7a00a838 100644
--- a/crates/viewer/re_viewer_context/src/drag_and_drop.rs
+++ b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
@@ -122,6 +122,7 @@ fn items_to_string<'a>(items: impl Iterator<Item = &'a Item>) -> String {
     let mut app_cnt = 0u32;
     let mut data_source_cnt = 0u32;
     let mut store_cnt = 0u32;
+    let mut entity_cnt = 0u32;
     let mut instance_cnt = 0u32;
     let mut component_cnt = 0u32;
 
@@ -132,9 +133,14 @@ fn items_to_string<'a>(items: impl Iterator<Item = &'a Item>) -> String {
             Item::AppId(_) => app_cnt += 1,
             Item::DataSource(_) => data_source_cnt += 1,
             Item::StoreId(_) => store_cnt += 1,
-            Item::InstancePath(_) => instance_cnt += 1,
+            Item::InstancePath(instance_path) | Item::DataResult(_, instance_path) => {
+                if instance_path.is_all() {
+                    entity_cnt += 1;
+                } else {
+                    instance_cnt += 1;
+                }
+            }
             Item::ComponentPath(_) => component_cnt += 1,
-            Item::DataResult(_, _) => instance_cnt += 1,
         }
     }
 
@@ -144,18 +150,20 @@ fn items_to_string<'a>(items: impl Iterator<Item = &'a Item>) -> String {
         &app_cnt,
         &data_source_cnt,
         &store_cnt,
+        &entity_cnt,
         &instance_cnt,
         &component_cnt,
     ];
 
     let names = [
-        "container",
-        "view",
-        "app",
-        "data source",
-        "store",
-        "instance",
-        "component",
+        ("container", "containers"),
+        ("view", "views"),
+        ("app", "apps"),
+        ("data source", "data sources"),
+        ("store", "stores"),
+        ("entity", "entities"),
+        ("instance", "instances"),
+        ("component", "components"),
     ];
 
     counts
@@ -164,10 +172,9 @@ fn items_to_string<'a>(items: impl Iterator<Item = &'a Item>) -> String {
         .filter_map(|(&&cnt, &name)| {
             if cnt > 0 {
                 Some(format!(
-                    "{} {}{}",
+                    "{} {}",
                     cnt,
-                    name,
-                    if cnt > 1 { "s" } else { "" }
+                    if cnt == 1 { name.0 } else { name.1 },
                 ))
             } else {
                 None

From d97bdaef5d84fccd0a7fba382cd74d335e90284e Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Mon, 9 Dec 2024 11:10:57 +0100
Subject: [PATCH 08/14] No longer draw the pill with invalid selection

---
 crates/viewer/re_viewer_context/src/drag_and_drop.rs | 12 ++++++------
 .../viewer/re_viewer_context/src/viewer_context.rs   |  8 +++-----
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/crates/viewer/re_viewer_context/src/drag_and_drop.rs b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
index 41ce7a00a838..adc34b13917a 100644
--- a/crates/viewer/re_viewer_context/src/drag_and_drop.rs
+++ b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
@@ -20,7 +20,7 @@ pub enum DragAndDropPayload {
     Contents { contents: Vec<Contents> },
 
     /// The dragged content is made of a collection of [`Item`]s we do know how to handle.
-    Invalid { items: crate::ItemCollection },
+    Invalid,
 }
 
 impl DragAndDropPayload {
@@ -28,9 +28,7 @@ impl DragAndDropPayload {
         if let Ok(contents) = (&selected_items).try_into() {
             Self::Contents { contents }
         } else {
-            Self::Invalid {
-                items: selected_items,
-            }
+            Self::Invalid
         }
     }
 }
@@ -47,7 +45,8 @@ impl std::fmt::Display for DragAndDropPayload {
             )
             .fmt(f),
 
-            Self::Invalid { items } => items_to_string(items.iter_items()).fmt(f),
+            // this is not used in the UI
+            Self::Invalid => "invalid selection".fmt(f),
         }
     }
 }
@@ -60,7 +59,8 @@ pub fn drag_and_drop_payload_cursor_ui(ui: &mut egui::Ui) {
         if let Some(pointer_pos) = ui.ctx().pointer_interact_pos() {
             let icon = match payload.as_ref() {
                 DragAndDropPayload::Contents { .. } => &re_ui::icons::DND_MOVE,
-                DragAndDropPayload::Invalid { .. } => &re_ui::icons::DND_CANNOT_USE,
+                // don't draw anything for invalid selection
+                DragAndDropPayload::Invalid => return,
             };
 
             let layer_id = egui::LayerId::new(
diff --git a/crates/viewer/re_viewer_context/src/viewer_context.rs b/crates/viewer/re_viewer_context/src/viewer_context.rs
index 72748e05fb6c..3fe195d45411 100644
--- a/crates/viewer/re_viewer_context/src/viewer_context.rs
+++ b/crates/viewer/re_viewer_context/src/viewer_context.rs
@@ -167,17 +167,15 @@ impl ViewerContext<'_> {
                 selection_state.set_selection(selected_items.clone());
             }
 
-            let is_selection_draggable = self
+            let selection_contains_undraggable_items = self
                 .undraggable_items
                 .iter_items()
                 .all(|item| !selected_items.contains_item(item));
 
-            let payload = if is_selection_draggable {
+            let payload = if selection_contains_undraggable_items {
                 DragAndDropPayload::from_items(selected_items)
             } else {
-                DragAndDropPayload::Invalid {
-                    items: selected_items,
-                }
+                DragAndDropPayload::Invalid
             };
 
             egui::DragAndDrop::set_payload(&response.ctx, payload);

From 4cede3e7ff2bd205ca249cb1028a02a0d7f3e384 Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Mon, 9 Dec 2024 16:06:54 +0100
Subject: [PATCH 09/14] Cleanup moving code

---
 Cargo.lock                                    | 22 +++++++++----------
 Cargo.toml                                    | 14 ++++++------
 .../re_blueprint_tree/src/blueprint_tree.rs   | 16 +++++---------
 .../re_viewer_context/src/drag_and_drop.rs    |  4 ++--
 .../re_viewer_context/src/viewer_context.rs   |  2 +-
 crates/viewer/re_viewport/src/viewport_ui.rs  | 22 ++++++++++++-------
 .../src/viewport_blueprint.rs                 |  4 ++--
 .../src/viewport_command.rs                   |  2 +-
 8 files changed, 43 insertions(+), 43 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 188ca2f77f5f..f9f9b46952e5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1923,7 +1923,7 @@ checksum = "0d6ef0072f8a535281e4876be788938b528e9a1d43900b82c2569af7da799125"
 [[package]]
 name = "ecolor"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
+source = "git+https://github.com/emilk/egui.git?rev=13352d606496d7b1c5fd6fcfbe3c85baae39c040#13352d606496d7b1c5fd6fcfbe3c85baae39c040"
 dependencies = [
  "bytemuck",
  "color-hex",
@@ -1940,7 +1940,7 @@ checksum = "18aade80d5e09429040243ce1143ddc08a92d7a22820ac512610410a4dd5214f"
 [[package]]
 name = "eframe"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
+source = "git+https://github.com/emilk/egui.git?rev=13352d606496d7b1c5fd6fcfbe3c85baae39c040#13352d606496d7b1c5fd6fcfbe3c85baae39c040"
 dependencies = [
  "ahash",
  "bytemuck",
@@ -1979,7 +1979,7 @@ dependencies = [
 [[package]]
 name = "egui"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
+source = "git+https://github.com/emilk/egui.git?rev=13352d606496d7b1c5fd6fcfbe3c85baae39c040#13352d606496d7b1c5fd6fcfbe3c85baae39c040"
 dependencies = [
  "accesskit",
  "ahash",
@@ -1996,7 +1996,7 @@ dependencies = [
 [[package]]
 name = "egui-wgpu"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
+source = "git+https://github.com/emilk/egui.git?rev=13352d606496d7b1c5fd6fcfbe3c85baae39c040#13352d606496d7b1c5fd6fcfbe3c85baae39c040"
 dependencies = [
  "ahash",
  "bytemuck",
@@ -2015,7 +2015,7 @@ dependencies = [
 [[package]]
 name = "egui-winit"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
+source = "git+https://github.com/emilk/egui.git?rev=13352d606496d7b1c5fd6fcfbe3c85baae39c040#13352d606496d7b1c5fd6fcfbe3c85baae39c040"
 dependencies = [
  "accesskit_winit",
  "ahash",
@@ -2057,7 +2057,7 @@ dependencies = [
 [[package]]
 name = "egui_extras"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
+source = "git+https://github.com/emilk/egui.git?rev=13352d606496d7b1c5fd6fcfbe3c85baae39c040#13352d606496d7b1c5fd6fcfbe3c85baae39c040"
 dependencies = [
  "ahash",
  "egui",
@@ -2074,7 +2074,7 @@ dependencies = [
 [[package]]
 name = "egui_glow"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
+source = "git+https://github.com/emilk/egui.git?rev=13352d606496d7b1c5fd6fcfbe3c85baae39c040#13352d606496d7b1c5fd6fcfbe3c85baae39c040"
 dependencies = [
  "ahash",
  "bytemuck",
@@ -2092,7 +2092,7 @@ dependencies = [
 [[package]]
 name = "egui_kittest"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
+source = "git+https://github.com/emilk/egui.git?rev=13352d606496d7b1c5fd6fcfbe3c85baae39c040#13352d606496d7b1c5fd6fcfbe3c85baae39c040"
 dependencies = [
  "dify",
  "egui",
@@ -2161,7 +2161,7 @@ checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
 [[package]]
 name = "emath"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
+source = "git+https://github.com/emilk/egui.git?rev=13352d606496d7b1c5fd6fcfbe3c85baae39c040#13352d606496d7b1c5fd6fcfbe3c85baae39c040"
 dependencies = [
  "bytemuck",
  "serde",
@@ -2277,7 +2277,7 @@ dependencies = [
 [[package]]
 name = "epaint"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
+source = "git+https://github.com/emilk/egui.git?rev=13352d606496d7b1c5fd6fcfbe3c85baae39c040#13352d606496d7b1c5fd6fcfbe3c85baae39c040"
 dependencies = [
  "ab_glyph",
  "ahash",
@@ -2296,7 +2296,7 @@ dependencies = [
 [[package]]
 name = "epaint_default_fonts"
 version = "0.29.1"
-source = "git+https://github.com/emilk/egui.git?rev=f687b27efc590b9584bfa6dd0c2f22edaf8c8cef#f687b27efc590b9584bfa6dd0c2f22edaf8c8cef"
+source = "git+https://github.com/emilk/egui.git?rev=13352d606496d7b1c5fd6fcfbe3c85baae39c040#13352d606496d7b1c5fd6fcfbe3c85baae39c040"
 
 [[package]]
 name = "equivalent"
diff --git a/Cargo.toml b/Cargo.toml
index 05ddd0ae4b8d..17e3ebe2c33b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -559,13 +559,13 @@ significant_drop_tightening = "allow" # An update of parking_lot made this trigg
 # As a last resport, patch with a commit to our own repository.
 # ALWAYS document what PR the commit hash is part of, or when it was merged into the upstream trunk.
 
-ecolor = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }       # egui master 2024-12-04
-eframe = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }       # egui master 2024-12-04
-egui = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }         # egui master 2024-12-04
-egui_extras = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }  # egui master 2024-12-04
-egui_kittest = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" } # egui master 2024-12-04
-egui-wgpu = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }    # egui master 2024-12-04
-emath = { git = "https://github.com/emilk/egui.git", rev = "f687b27efc590b9584bfa6dd0c2f22edaf8c8cef" }        # egui master 2024-12-04
+ecolor = { git = "https://github.com/emilk/egui.git", rev = "13352d606496d7b1c5fd6fcfbe3c85baae39c040" }       # egui master 2024-12-09
+eframe = { git = "https://github.com/emilk/egui.git", rev = "13352d606496d7b1c5fd6fcfbe3c85baae39c040" }       # egui master 2024-12-09
+egui = { git = "https://github.com/emilk/egui.git", rev = "13352d606496d7b1c5fd6fcfbe3c85baae39c040" }         # egui master 2024-12-09
+egui_extras = { git = "https://github.com/emilk/egui.git", rev = "13352d606496d7b1c5fd6fcfbe3c85baae39c040" }  # egui master 2024-12-09
+egui_kittest = { git = "https://github.com/emilk/egui.git", rev = "13352d606496d7b1c5fd6fcfbe3c85baae39c040" } # egui master 2024-12-09
+egui-wgpu = { git = "https://github.com/emilk/egui.git", rev = "13352d606496d7b1c5fd6fcfbe3c85baae39c040" }    # egui master 2024-12-09
+emath = { git = "https://github.com/emilk/egui.git", rev = "13352d606496d7b1c5fd6fcfbe3c85baae39c040" }        # egui master 2024-12-09
 
 # Useful while developing:
 # ecolor = { path = "../../egui/crates/ecolor" }
diff --git a/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs b/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
index 8554f490dc4b..11ca450124da 100644
--- a/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
+++ b/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
@@ -837,17 +837,11 @@ impl BlueprintTree {
         };
 
         if ui.input(|i| i.pointer.any_released()) {
-            for (idx, content) in dragged_contents.iter().enumerate() {
-                // TODO: this is not strictly correct when dragging multiple items inside the same
-                // container, as the position are all over the place when moving items incrementally.
-                // We probably need a `viewport.move_multiple_contents()` method which handles this
-                // correctly.
-                viewport.move_contents(
-                    *content,
-                    target_container_id,
-                    drop_target.target_position_index + idx,
-                );
-            }
+            viewport.move_contents(
+                dragged_contents,
+                target_container_id,
+                drop_target.target_position_index,
+            );
 
             egui::DragAndDrop::clear_payload(ui.ctx());
         } else {
diff --git a/crates/viewer/re_viewer_context/src/drag_and_drop.rs b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
index adc34b13917a..1849acef1d12 100644
--- a/crates/viewer/re_viewer_context/src/drag_and_drop.rs
+++ b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
@@ -24,8 +24,8 @@ pub enum DragAndDropPayload {
 }
 
 impl DragAndDropPayload {
-    pub fn from_items(selected_items: ItemCollection) -> Self {
-        if let Ok(contents) = (&selected_items).try_into() {
+    pub fn from_items(selected_items: &ItemCollection) -> Self {
+        if let Ok(contents) = selected_items.try_into() {
             Self::Contents { contents }
         } else {
             Self::Invalid
diff --git a/crates/viewer/re_viewer_context/src/viewer_context.rs b/crates/viewer/re_viewer_context/src/viewer_context.rs
index 3fe195d45411..81c93f00d118 100644
--- a/crates/viewer/re_viewer_context/src/viewer_context.rs
+++ b/crates/viewer/re_viewer_context/src/viewer_context.rs
@@ -173,7 +173,7 @@ impl ViewerContext<'_> {
                 .all(|item| !selected_items.contains_item(item));
 
             let payload = if selection_contains_undraggable_items {
-                DragAndDropPayload::from_items(selected_items)
+                DragAndDropPayload::from_items(&selected_items)
             } else {
                 DragAndDropPayload::Invalid
             };
diff --git a/crates/viewer/re_viewport/src/viewport_ui.rs b/crates/viewer/re_viewport/src/viewport_ui.rs
index d4253995ff2d..558fe202d996 100644
--- a/crates/viewer/re_viewport/src/viewport_ui.rs
+++ b/crates/viewer/re_viewport/src/viewport_ui.rs
@@ -379,15 +379,21 @@ fn apply_viewport_command(
                         {target_position_in_container}"
             );
 
-            let contents_tile_id = contents_to_move.as_tile_id();
-            let target_container_tile_id = blueprint_id_to_tile_id(&target_container);
+            // TODO(ab): the `rev()` is better preserve ordering when moving a group of items. There
+            // remains some ordering (and possibly insertion point error) edge cases when dragging
+            // multiple item within the same container. This should be addressed by egui_tiles:
+            // https://github.com/rerun-io/egui_tiles/issues/90
+            for contents in contents_to_move.iter().rev() {
+                let contents_tile_id = contents.as_tile_id();
+                let target_container_tile_id = blueprint_id_to_tile_id(&target_container);
 
-            bp.tree.move_tile_to_container(
-                contents_tile_id,
-                target_container_tile_id,
-                target_position_in_container,
-                true,
-            );
+                bp.tree.move_tile_to_container(
+                    contents_tile_id,
+                    target_container_tile_id,
+                    target_position_in_container,
+                    true,
+                );
+            }
         }
 
         ViewportCommand::MoveContentsToNewContainer {
diff --git a/crates/viewer/re_viewport_blueprint/src/viewport_blueprint.rs b/crates/viewer/re_viewport_blueprint/src/viewport_blueprint.rs
index c8453466ef1f..1416c9eefa8d 100644
--- a/crates/viewer/re_viewport_blueprint/src/viewport_blueprint.rs
+++ b/crates/viewer/re_viewport_blueprint/src/viewport_blueprint.rs
@@ -583,12 +583,12 @@ impl ViewportBlueprint {
     /// Move the `contents` container or space view to the specified target container and position.
     pub fn move_contents(
         &self,
-        contents: Contents,
+        contents: &[Contents],
         target_container: ContainerId,
         target_position_in_container: usize,
     ) {
         self.enqueue_command(ViewportCommand::MoveContents {
-            contents_to_move: contents,
+            contents_to_move: contents.to_vec(),
             target_container,
             target_position_in_container,
         });
diff --git a/crates/viewer/re_viewport_blueprint/src/viewport_command.rs b/crates/viewer/re_viewport_blueprint/src/viewport_command.rs
index e4056b51f8a2..0d74b160dd90 100644
--- a/crates/viewer/re_viewport_blueprint/src/viewport_command.rs
+++ b/crates/viewer/re_viewport_blueprint/src/viewport_command.rs
@@ -40,7 +40,7 @@ pub enum ViewportCommand {
 
     /// Move some contents to a different container
     MoveContents {
-        contents_to_move: Contents,
+        contents_to_move: Vec<Contents>,
         target_container: ContainerId,
         target_position_in_container: usize,
     },

From 0ceb78658f032d47256c61ed81898b44a593d29b Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Mon, 9 Dec 2024 16:19:02 +0100
Subject: [PATCH 10/14] remove unnecessary icon

---
 crates/viewer/re_ui/data/icons/dnd_cannot_use.png | Bin 685 -> 0 bytes
 crates/viewer/re_ui/src/icons.rs                  |   1 -
 2 files changed, 1 deletion(-)
 delete mode 100644 crates/viewer/re_ui/data/icons/dnd_cannot_use.png

diff --git a/crates/viewer/re_ui/data/icons/dnd_cannot_use.png b/crates/viewer/re_ui/data/icons/dnd_cannot_use.png
deleted file mode 100644
index db1ba198f7441a6b9517e5e662285243f219aefb..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

literal 685
zcmV;e0#f~nP)<h;3K|Lk000e1NJLTq000~S000~a1^@s6at+^<00009a7bBm000&x
z000&x0ZCFM@Bjb+0drDELIAGL9O(c600d`2O+f$vv5yP<VFdsH0zyedK~#7F?N&{4
z(=Zf%Qd(e{BiPd!AS>EM%d+MMaD(2U;RK0Kka7YhH{b>_D+XuLvPznnAajGTV_MMT
zeg2uY#)_5D?)uF*QZ#z{q)+chM31;<DBp?c!t7gXBdzo+Vh%9I#49HH{FL>lgI<{V
ztkX(3otcOg52PEFLz$RmMVGtsvtN!Uq}BVQ=ivoyOE_Ja5nJwqgqg=rp6RoLFkIc9
z^JQj&4mMM4Do{!d4_|~aZHn}A`7xb;=XAb2J2$55WAk;k9OgD+>zbpR2B(*1K&(#W
zRPoWvy?*^v&c(Fmyd$>hVmWG>^N*x(4zhd>ve&)6A$bCu6q_OJlp;|?ohnvu4trs;
z)-au$iO6DT1Aq)tLQ?$46<`hdCiS^@B!vTr9+61med)JPRw;rjfRjl#$`x}FiWG0r
z?!v{lB&z_AMvK^W5_ZTQOLO59#Oug_($TUVBnlTHlZN}ZdSn~f4OC{!tkg*81Anq+
z+&v-l4`~9rCo(0e&szHFCR7S}Flfpwo07rf8F^N7;w03%@Xo7Ww*Nn5K!^TBXi-Vl
zPOJjII%Pemec=lHo%(=cidoU*`q~bJY_*Mpl!^pWuHJbWph6UtV)K)=Dbg4gs1VF{
zoKL7KKnrjMdHu{4v16AaYYQ-TDFqdUH6yn1E_IT676Q@lD>@aT6Usx1KVZYIHCvw;
zMY*C;p41B<bgFC=&`sPXQjX%ba^(GpLR=xa%Xch})h(?hb<sD3Q`=kS5f6sHL#CKQ
T?ita+00000NkvXXu0mjf<?%5#

diff --git a/crates/viewer/re_ui/src/icons.rs b/crates/viewer/re_ui/src/icons.rs
index f31037b70344..c4be5b7a5305 100644
--- a/crates/viewer/re_ui/src/icons.rs
+++ b/crates/viewer/re_ui/src/icons.rs
@@ -131,7 +131,6 @@ pub const VIDEO_ERROR: Icon = icon_from_path!("../data/icons/video_error.png");
 // drag and drop icons
 pub const DND_ADD_NEW: Icon = icon_from_path!("../data/icons/dnd_add_new.png");
 pub const DND_ADD_TO_EXISTING: Icon = icon_from_path!("../data/icons/dnd_add_to_existing.png");
-pub const DND_CANNOT_USE: Icon = icon_from_path!("../data/icons/dnd_cannot_use.png");
 pub const DND_MOVE: Icon = icon_from_path!("../data/icons/dnd_move.png");
 
 /// `>`

From ba14e6a29609677c5b3b459b4061760bc66fa042 Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Wed, 11 Dec 2024 15:56:42 +0100
Subject: [PATCH 11/14] Addressed some review comments

---
 .../re_blueprint_tree/src/blueprint_tree.rs   |  9 ++--
 crates/viewer/re_viewer/src/app_state.rs      |  2 +-
 .../re_viewer_context/src/drag_and_drop.rs    | 54 ++++++++++---------
 .../re_viewer_context/src/viewer_context.rs   | 10 +++-
 .../src/viewport_blueprint.rs                 |  4 +-
 5 files changed, 45 insertions(+), 34 deletions(-)

diff --git a/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs b/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
index 86d432262df1..d22b70d8c987 100644
--- a/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
+++ b/crates/viewer/re_blueprint_tree/src/blueprint_tree.rs
@@ -805,8 +805,8 @@ impl BlueprintTree {
     ) {
         // We cannot allow the target location to be "inside" any of the dragged items, because that
         // would amount to moving myself inside of me.
-        if dragged_contents.iter().any(|dragged_contents| {
-            if let Contents::Container(dragged_container_id) = dragged_contents {
+        let parent_contains_dragged_content = |content: &Contents| {
+            if let Contents::Container(dragged_container_id) = content {
                 if viewport
                     .is_contents_in_container(&drop_target.target_parent_id, dragged_container_id)
                 {
@@ -814,7 +814,8 @@ impl BlueprintTree {
                 }
             }
             false
-        }) {
+        };
+        if dragged_contents.iter().any(parent_contains_dragged_content) {
             return;
         }
 
@@ -831,7 +832,7 @@ impl BlueprintTree {
 
         if ui.input(|i| i.pointer.any_released()) {
             viewport.move_contents(
-                dragged_contents,
+                dragged_contents.to_vec(),
                 target_container_id,
                 drop_target.target_position_index,
             );
diff --git a/crates/viewer/re_viewer/src/app_state.rs b/crates/viewer/re_viewer/src/app_state.rs
index 2a8317102370..8e07b53d6c7c 100644
--- a/crates/viewer/re_viewer/src/app_state.rs
+++ b/crates/viewer/re_viewer/src/app_state.rs
@@ -512,7 +512,7 @@ impl AppState {
         //
 
         add_view_or_container_modal_ui(&ctx, &viewport_ui.blueprint, ui);
-        drag_and_drop_payload_cursor_ui(ui);
+        drag_and_drop_payload_cursor_ui(ctx.egui_ctx);
 
         // Process deferred layout operations and apply updates back to blueprint:
         viewport_ui.save_to_blueprint_store(&ctx, view_class_registry);
diff --git a/crates/viewer/re_viewer_context/src/drag_and_drop.rs b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
index 95f50712dc0c..fe8a4638fa65 100644
--- a/crates/viewer/re_viewer_context/src/drag_and_drop.rs
+++ b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
@@ -54,9 +54,9 @@ impl std::fmt::Display for DragAndDropPayload {
 /// Display the currently dragged payload as a pill in the UI.
 ///
 /// This should be called once per frame.
-pub fn drag_and_drop_payload_cursor_ui(ui: &mut egui::Ui) {
-    if let Some(payload) = egui::DragAndDrop::payload::<DragAndDropPayload>(ui.ctx()) {
-        if let Some(pointer_pos) = ui.ctx().pointer_interact_pos() {
+pub fn drag_and_drop_payload_cursor_ui(ctx: &egui::Context) {
+    if let Some(payload) = egui::DragAndDrop::payload::<DragAndDropPayload>(ctx) {
+        if let Some(pointer_pos) = ctx.pointer_interact_pos() {
             let icon = match payload.as_ref() {
                 DragAndDropPayload::Contents { .. } => &re_ui::icons::DND_MOVE,
                 // don't draw anything for invalid selection
@@ -67,31 +67,33 @@ pub fn drag_and_drop_payload_cursor_ui(ui: &mut egui::Ui) {
                 egui::Order::Tooltip,
                 egui::Id::new("drag_and_drop_payload_layer"),
             );
-            let response = ui
-                .scope_builder(egui::UiBuilder::new().layer_id(layer_id), |ui| {
-                    ui.set_opacity(0.7);
-
-                    drag_pill_frame(matches!(
-                        payload.as_ref(),
-                        &DragAndDropPayload::Invalid { .. }
-                    ))
-                    .show(ui, |ui| {
-                        let text_color = ui.visuals().widgets.inactive.text_color();
-
-                        ui.horizontal(|ui| {
-                            ui.spacing_mut().item_spacing.x = 2.0;
-
-                            ui.small_icon(icon, Some(text_color));
-                            ui.label(egui::RichText::new(payload.to_string()).color(text_color));
-                        });
-                    })
-                    .response
-                })
-                .response;
+
+            let mut ui = egui::Ui::new(
+                ctx.clone(),
+                egui::Id::new("rerun_drag_and_drop_payload_ui"),
+                egui::UiBuilder::new().layer_id(layer_id),
+            );
+
+            ui.set_opacity(0.7);
+
+            let response = drag_pill_frame(matches!(
+                payload.as_ref(),
+                &DragAndDropPayload::Invalid { .. }
+            ))
+            .show(&mut ui, |ui| {
+                let text_color = ui.visuals().widgets.inactive.text_color();
+
+                ui.horizontal(|ui| {
+                    ui.spacing_mut().item_spacing.x = 2.0;
+
+                    ui.small_icon(icon, Some(text_color));
+                    ui.label(egui::RichText::new(payload.to_string()).color(text_color));
+                });
+            })
+            .response;
 
             let delta = pointer_pos - response.rect.right_bottom();
-            ui.ctx()
-                .transform_layer_shapes(layer_id, emath::TSTransform::from_translation(delta));
+            ctx.transform_layer_shapes(layer_id, emath::TSTransform::from_translation(delta));
         }
     }
 }
diff --git a/crates/viewer/re_viewer_context/src/viewer_context.rs b/crates/viewer/re_viewer_context/src/viewer_context.rs
index 48e97a5f6168..f2ba3af23e5a 100644
--- a/crates/viewer/re_viewer_context/src/viewer_context.rs
+++ b/crates/viewer/re_viewer_context/src/viewer_context.rs
@@ -137,7 +137,15 @@ impl ViewerContext<'_> {
 
     /// Consistently handle the selection, hover, drag start interactions for a given set of items.
     ///
-    /// The drag start interaction is optional and controlled by the `draggable` parameter.
+    /// The `draggable` parameter controls whether a drag can be initiated from this item. When a UI
+    /// element represents an [`Item`], one must make the call whether this element should be
+    /// meaningfully draggable by the users. This is ultimately a subjective decision, but some here
+    /// are some guidelines:
+    /// - Is there a meaningful destination for the dragged payload? For example, dragging stuff out
+    ///   of a modal dialog is by definition meaningless.
+    /// - Even if a drag destination exists, would that be obvious for the user?
+    /// - Is it expected for that kind of UI element to be draggable? For example, buttons aren't
+    ///   typically draggable.
     pub fn handle_select_hover_drag_interactions(
         &self,
         response: &egui::Response,
diff --git a/crates/viewer/re_viewport_blueprint/src/viewport_blueprint.rs b/crates/viewer/re_viewport_blueprint/src/viewport_blueprint.rs
index 81d09f08d844..911e53bc3956 100644
--- a/crates/viewer/re_viewport_blueprint/src/viewport_blueprint.rs
+++ b/crates/viewer/re_viewport_blueprint/src/viewport_blueprint.rs
@@ -572,12 +572,12 @@ impl ViewportBlueprint {
     /// Move the `contents` container or view to the specified target container and position.
     pub fn move_contents(
         &self,
-        contents: &[Contents],
+        contents_to_move: Vec<Contents>,
         target_container: ContainerId,
         target_position_in_container: usize,
     ) {
         self.enqueue_command(ViewportCommand::MoveContents {
-            contents_to_move: contents.to_vec(),
+            contents_to_move,
             target_container,
             target_position_in_container,
         });

From 5242225f42b97956a7a1f0740a427694bf6cd907 Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <49431240+abey79@users.noreply.github.com>
Date: Wed, 11 Dec 2024 16:00:05 +0100
Subject: [PATCH 12/14] Update
 crates/viewer/re_viewer_context/src/drag_and_drop.rs

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
---
 .../re_viewer_context/src/drag_and_drop.rs    | 36 +++++++------------
 1 file changed, 12 insertions(+), 24 deletions(-)

diff --git a/crates/viewer/re_viewer_context/src/drag_and_drop.rs b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
index fe8a4638fa65..3264554b6c4d 100644
--- a/crates/viewer/re_viewer_context/src/drag_and_drop.rs
+++ b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
@@ -146,32 +146,20 @@ fn items_to_string<'a>(items: impl Iterator<Item = &'a Item>) -> String {
         }
     }
 
-    let counts = [
-        &container_cnt,
-        &view_cnt,
-        &app_cnt,
-        &data_source_cnt,
-        &store_cnt,
-        &entity_cnt,
-        &instance_cnt,
-        &component_cnt,
+    let count_and_names = [
+        (container_cnt, "container", "containers"),
+        (view_cnt, "view", "views"),
+        (app_cnt, "app", "apps"),
+        (data_source_cnt, "data source", "data sources"),
+        (store_cnt, "store", "stores"),
+        (entity_cnt, "entity", "entities"),
+        (instance_cnt, "instance", "instances"),
+        (component_cnt, "component", "components"),
     ];
 
-    let names = [
-        ("container", "containers"),
-        ("view", "views"),
-        ("app", "apps"),
-        ("data source", "data sources"),
-        ("store", "stores"),
-        ("entity", "entities"),
-        ("instance", "instances"),
-        ("component", "components"),
-    ];
-
-    counts
-        .iter()
-        .zip(names.iter())
-        .filter_map(|(&&cnt, &name)| {
+    count_and_names
+        .into_iter()
+        .filter_map(|(count, name_singular, name_plural)| {
             if cnt > 0 {
                 Some(format!(
                     "{} {}",

From b6753cd76bf4fbd4f5d338232918c063011df8ae Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Wed, 11 Dec 2024 16:07:15 +0100
Subject: [PATCH 13/14] More review comments

---
 crates/viewer/re_viewer_context/src/drag_and_drop.rs  | 10 +++++++---
 crates/viewer/re_viewer_context/src/viewer_context.rs |  4 ++--
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/crates/viewer/re_viewer_context/src/drag_and_drop.rs b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
index 3264554b6c4d..bec7e7e43a5f 100644
--- a/crates/viewer/re_viewer_context/src/drag_and_drop.rs
+++ b/crates/viewer/re_viewer_context/src/drag_and_drop.rs
@@ -160,11 +160,15 @@ fn items_to_string<'a>(items: impl Iterator<Item = &'a Item>) -> String {
     count_and_names
         .into_iter()
         .filter_map(|(count, name_singular, name_plural)| {
-            if cnt > 0 {
+            if count > 0 {
                 Some(format!(
                     "{} {}",
-                    cnt,
-                    if cnt == 1 { name.0 } else { name.1 },
+                    re_format::format_uint(count),
+                    if count == 1 {
+                        name_singular
+                    } else {
+                        name_plural
+                    },
                 ))
             } else {
                 None
diff --git a/crates/viewer/re_viewer_context/src/viewer_context.rs b/crates/viewer/re_viewer_context/src/viewer_context.rs
index f2ba3af23e5a..9d0a414cdc37 100644
--- a/crates/viewer/re_viewer_context/src/viewer_context.rs
+++ b/crates/viewer/re_viewer_context/src/viewer_context.rs
@@ -175,12 +175,12 @@ impl ViewerContext<'_> {
                 selection_state.set_selection(selected_items.clone());
             }
 
-            let selection_contains_undraggable_items = self
+            let selection_may_be_dragged = self
                 .undraggable_items
                 .iter_items()
                 .all(|item| !selected_items.contains_item(item));
 
-            let payload = if selection_contains_undraggable_items {
+            let payload = if selection_may_be_dragged {
                 DragAndDropPayload::from_items(&selected_items)
             } else {
                 DragAndDropPayload::Invalid

From 245210ac3c10dbc73ca43f5e41c02d70c6fd64cd Mon Sep 17 00:00:00 2001
From: Antoine Beyeler <antoine@rerun.io>
Date: Wed, 11 Dec 2024 17:32:19 +0100
Subject: [PATCH 14/14] Add TODO + fix doclink

---
 crates/viewer/re_viewer_context/src/viewer_context.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/crates/viewer/re_viewer_context/src/viewer_context.rs b/crates/viewer/re_viewer_context/src/viewer_context.rs
index 9d0a414cdc37..1b1d470dc7c5 100644
--- a/crates/viewer/re_viewer_context/src/viewer_context.rs
+++ b/crates/viewer/re_viewer_context/src/viewer_context.rs
@@ -82,6 +82,10 @@ pub struct ViewerContext<'a> {
     pub focused_item: &'a Option<crate::Item>,
 
     /// If a selection contains any `undraggable_items`, it may not be dragged.
+    ///
+    /// This is a rather ugly workaround to handle the case of the root container not being
+    /// draggable, but also being unknown to the drag-and-drop machinery in `re_viewer_context`.
+    //TODO(ab): figure out a way to deal with that in a cleaner way.
     pub undraggable_items: &'a ItemCollection,
 }
 
@@ -138,7 +142,7 @@ impl ViewerContext<'_> {
     /// Consistently handle the selection, hover, drag start interactions for a given set of items.
     ///
     /// The `draggable` parameter controls whether a drag can be initiated from this item. When a UI
-    /// element represents an [`Item`], one must make the call whether this element should be
+    /// element represents an [`crate::Item`], one must make the call whether this element should be
     /// meaningfully draggable by the users. This is ultimately a subjective decision, but some here
     /// are some guidelines:
     /// - Is there a meaningful destination for the dragged payload? For example, dragging stuff out