Feature: Implement Context Menu

[pewsheen]

Let's use this issue to update everything related to the context menu;

Current Status:

• Platforms:
  • Windows and macOS will use muda for native context menu support
    • feat: implement fixed context menu for mac and windows #226
    • feat: return context menu dismiss result tauri-apps/muda#236 Wait for Muda 0.16, trying to let selection be synchronous
  • Linux is not implemented in a native way at the moment
    • Since we are not using GTK, we'll need to draw the menu by openGL or any GUI library, then send the gl_surface to X11 or wl_surface in Wayland popup API. This will be complicated.
    • We have successfully made a popup on winit window, but it'll require some modification to the winit crate pewsheen/winit@73fad21
    • Winit plans to add popup support in the future, maybe 0.31?
    • feat(wayland): popup window #196
  • Linux is planning to use inner webview until the native popup is implemented
    • feat(context-menu): add linux webview context menu #237
• Servo
  • Servo does not emit ShowContextMenu for the moment. Let's see what we can help.
  • Will use a fixed context menu options until servo emits the ShowContextMenu event
  • The interface of Servo ShowContextMenuEvent may need some refactoring, like bringing the webview ID and what the user has selected (link? plain-text? or nothing) and letting the embedder decide what options to show.

[wusyong]

Since wayland doesn't have any menu support and winit hasn't provide trait to create popup surface for wayland yet.
We decided to go with webview implementation on wayland first. Here's how it looks on my device:

2.mp4

[wusyong]

Windows and macOS, on the other hand, have the support. And we can utilize the muda crate from Tauri.

context-menu.mp4