Broken multirow feature on FF 131 and above

[Druzai]

Describe the bug

After updating Firefox to version 131 and above, the tab bar doesn't create multiple rows of tabs when it's expected to.

Expected behavior

Create 2nd row of tabs after exceeding the tab limit in 1st row.

Screenshots

Broken multirow

OS

Windows 10

OS - Others

No response

Firefox Version

v132.0.1

Distribution

• Original Lepton
• Lepton's photon style
• Lepton's proton style

Theme

• Light
• Dark
• Alpenglow (System: Light)
• Alpenglow (System: Dark)
• System Default
• Others: (e.g. Photon Colors, Google Chrome Dark, Fairytale Of Nature)

Theme - More Info

No response

user.js setup

user.js setup

user_pref("browser.tabs.tabMinWidth", 57);
// ** Theme Default Options ****************************************************
// userchrome.css usercontent.css activate
user_pref("toolkit.legacyUserProfileCustomizations.stylesheets", true);

// Fill SVG Color
user_pref("svg.context-properties.content.enabled", true);

// Restore Compact Mode - 89 Above
user_pref("browser.compactmode.show", true);

// about:home Search Bar - 89 Above
user_pref("browser.newtabpage.activity-stream.improvesearch.handoffToAwesomebar", false);

// CSS's `:has()` selector #457 - 103 Above
user_pref("layout.css.has-selector.enabled", true);

// Browser Theme Based Scheme - Will be activate 95 Above
// user_pref("layout.css.prefers-color-scheme.content-override", 3);

// ** Theme Related Options ****************************************************
// == Theme Distribution Settings ==============================================
// The rows that are located continuously must be changed `true`/`false` explicitly because there is a collision.
// https://github.com/black7375/Firefox-UI-Fix/wiki/Options#important
user_pref("userChrome.tab.connect_to_window",          true); // Original, Photon
user_pref("userChrome.tab.color_like_toolbar",         true); // Original, Photon

user_pref("userChrome.tab.lepton_like_padding",        true); // Original
user_pref("userChrome.tab.photon_like_padding",       false); // Photon

user_pref("userChrome.tab.dynamic_separator",          true); // Original, Proton
user_pref("userChrome.tab.static_separator",          false); // Photon
user_pref("userChrome.tab.static_separator.selected_accent", false); // Just option
user_pref("userChrome.tab.bar_separator",             false); // Just option

user_pref("userChrome.tab.newtab_button_like_tab",     true); // Original
user_pref("userChrome.tab.newtab_button_smaller",     false); // Photon
user_pref("userChrome.tab.newtab_button_proton",      false); // Proton

user_pref("userChrome.icon.panel_full",                true); // Original, Proton
user_pref("userChrome.icon.panel_photon",             false); // Photon

// Original Only
user_pref("userChrome.tab.box_shadow",                 true);
user_pref("userChrome.tab.bottom_rounded_corner",      true);

// Photon Only
user_pref("userChrome.tab.photon_like_contextline",   false);
user_pref("userChrome.rounding.square_tab",           false);

// Proton Only
// user_pref("userChrome.tab.supernova_like_contextline",   true);

// == Theme Compatibility Settings =============================================
// user_pref("userChrome.compatibility.accent_color",         true); // Firefox v103 Below
// user_pref("userChrome.compatibility.covered_header_image", true);
// user_pref("userChrome.compatibility.panel_cutoff",         true);
// user_pref("userChrome.compatibility.navbar_top_border",    true);
// user_pref("userChrome.compatibility.dynamic_separator",    true); // Need dynamic_separator

// user_pref("userChrome.compatibility.os.linux_non_native_titlebar_button", true);
// user_pref("userChrome.compatibility.os.windows_maximized", true);
// user_pref("userChrome.compatibility.os.win11",             true);

// == Theme Custom Settings ====================================================
// -- User Chrome --------------------------------------------------------------
// user_pref("userChrome.theme.private",                       true);
user_pref("userChrome.theme.proton_color.dark_blue_accent", true);
// user_pref("userChrome.theme.monospace",                     true);
// user_pref("userChrome.theme.transparent.frame",             true);
// user_pref("userChrome.theme.transparent.menu",              true);
// user_pref("userChrome.theme.transparent.panel",             true);
// user_pref("userChrome.theme.non_native_menu",               true); // only for linux

// user_pref("userChrome.decoration.disable_panel_animate",    true);
// user_pref("userChrome.decoration.disable_sidebar_animate",  true);
// user_pref("userChrome.decoration.panel_button_separator",   true);
// user_pref("userChrome.decoration.panel_arrow",              true);

// user_pref("userChrome.autohide.tab",                        true);
// user_pref("userChrome.autohide.tab.opacity",                true);
// user_pref("userChrome.autohide.tab.blur",                   true);
// user_pref("userChrome.autohide.tabbar",                     true);
// user_pref("userChrome.autohide.navbar",                     true);
// user_pref("userChrome.autohide.bookmarkbar",                true);
// user_pref("userChrome.autohide.sidebar",                    true);
// user_pref("userChrome.autohide.fill_urlbar",                true);
// user_pref("userChrome.autohide.back_button",                true);
// user_pref("userChrome.autohide.forward_button",             true);
// user_pref("userChrome.autohide.page_action",                true);
// user_pref("userChrome.autohide.toolbar_overlap",            true);
// user_pref("userChrome.autohide.toolbar_overlap.allow_layout_shift", true);

// user_pref("userChrome.hidden.tab_icon",                     true);
// user_pref("userChrome.hidden.tab_icon.always",              true);
// user_pref("userChrome.hidden.tabbar",                       true);
// user_pref("userChrome.hidden.navbar",                       true);
// user_pref("userChrome.hidden.private_indicator",            true);
// user_pref("userChrome.hidden.titlebar_container",           true);
// user_pref("userChrome.hidden.sidebar_header",               true);
// user_pref("userChrome.hidden.sidebar_header.vertical_tab_only", true);
// user_pref("userChrome.hidden.urlbar_iconbox",               true);
// user_pref("userChrome.hidden.urlbar_iconbox.label_only",    true);
// user_pref("userChrome.hidden.bookmarkbar_icon",             true);
// user_pref("userChrome.hidden.bookmarkbar_label",            true);
// user_pref("userChrome.hidden.disabled_menu",                true);

// user_pref("userChrome.centered.tab",                        true);
// user_pref("userChrome.centered.tab.label",                  true);
// user_pref("userChrome.centered.urlbar",                     true);
// user_pref("userChrome.centered.bookmarkbar",                true);

// user_pref("userChrome.counter.tab",                         true);
// user_pref("userChrome.counter.bookmark_menu",               true);

// user_pref("userChrome.combined.nav_button",                 true);
// user_pref("userChrome.combined.nav_button.home_button",     true);
// user_pref("userChrome.combined.urlbar.nav_button",          true);
// user_pref("userChrome.combined.urlbar.home_button",         true);
// user_pref("userChrome.combined.urlbar.reload_button",       true);
// user_pref("userChrome.combined.sub_button.none_background", true);
// user_pref("userChrome.combined.sub_button.as_normal",       true);

// user_pref("userChrome.rounding.square_button",              true);
// user_pref("userChrome.rounding.square_dialog",              true);
// user_pref("userChrome.rounding.square_panel",               true);
// user_pref("userChrome.rounding.square_panelitem",           true);
// user_pref("userChrome.rounding.square_menupopup",           true);
// user_pref("userChrome.rounding.square_menuitem",            true);
// user_pref("userChrome.rounding.square_infobox",             true);
// user_pref("userChrome.rounding.square_toolbar",             true);
// user_pref("userChrome.rounding.square_field",               true);
// user_pref("userChrome.rounding.square_urlView_item",        true);
// user_pref("userChrome.rounding.square_checklabel",          true);

// user_pref("userChrome.padding.first_tab",                   true);
// user_pref("userChrome.padding.first_tab.always",            true);
// user_pref("userChrome.padding.drag_space",                  true);
// user_pref("userChrome.padding.drag_space.maximized",        true);

// user_pref("userChrome.padding.toolbar_button.compact",      true);
// user_pref("userChrome.padding.menu_compact",                true);
// user_pref("userChrome.padding.bookmark_menu.compact",       true);
user_pref("userChrome.padding.urlView_expanding",           true);
user_pref("userChrome.padding.urlView_result",              true);
// user_pref("userChrome.padding.panel_header",                true);

// user_pref("userChrome.urlbar.iconbox_with_separator",       true);

// user_pref("userChrome.urlView.as_commandbar",               true);
// user_pref("userChrome.urlView.full_width_padding",          true);
// user_pref("userChrome.urlView.always_show_page_actions",    true);
// user_pref("userChrome.urlView.move_icon_to_left",           true);
user_pref("userChrome.urlView.go_button_when_typing",       true);
// user_pref("userChrome.urlView.focus_item_border",           true);

// user_pref("userChrome.tabbar.as_titlebar",                  true);
// user_pref("userChrome.tabbar.fill_width",                   true);
user_pref("userChrome.tabbar.multi_row",                    true);
// user_pref("userChrome.tabbar.unscroll",                     true);
// user_pref("userChrome.tabbar.on_bottom",                    true);
// user_pref("userChrome.tabbar.on_bottom.above_bookmark",     true); // Need on_bottom
// user_pref("userChrome.tabbar.on_bottom.menubar_on_top",     true); // Need on_bottom
// user_pref("userChrome.tabbar.on_bottom.hidden_single_tab",  true); // Need on_bottom
// user_pref("userChrome.tabbar.one_liner",                    true);
// user_pref("userChrome.tabbar.one_liner.combine_navbar",     true); // Need one_liner
// user_pref("userChrome.tabbar.one_liner.tabbar_first",       true); // Need one_liner
// user_pref("userChrome.tabbar.one_liner.responsive",         true); // Need one_liner

// user_pref("userChrome.tab.bottom_rounded_corner.all",       true);
// user_pref("userChrome.tab.bottom_rounded_corner.australis", true);
// user_pref("userChrome.tab.bottom_rounded_corner.edge",      true);
// user_pref("userChrome.tab.bottom_rounded_corner.chrome",    true);
// user_pref("userChrome.tab.bottom_rounded_corner.chrome_legacy", true);
// user_pref("userChrome.tab.bottom_rounded_corner.wave",      true);
// user_pref("userChrome.tab.always_show_tab_icon",            true);
// user_pref("userChrome.tab.close_button_at_pinned",          true);
// user_pref("userChrome.tab.close_button_at_pinned.always",   true);
// user_pref("userChrome.tab.close_button_at_pinned.background", true);
// user_pref("userChrome.tab.close_button_at_hover.always",    true); // Need close_button_at_hover
// user_pref("userChrome.tab.close_button_at_hover.with_selected", true);  // Need close_button_at_hover
// user_pref("userChrome.tab.sound_show_label",                true); // Need remove sound_hide_label
// user_pref("userChrome.tab.container.on_top",                true);
// user_pref("userChrome.tab.container.always_long",           true);
// user_pref("userChrome.tab.sound_with_favicons.on_center",   true);
// user_pref("userChrome.tab.selected_bold",                   true);

// user_pref("userChrome.navbar.as_sidebar",                   true);

// user_pref("userChrome.bookmarkbar.multi_row",               true);

// user_pref("userChrome.findbar.floating_on_top",             true);

user_pref("userChrome.panel.remove_strip",                  true);
// user_pref("userChrome.panel.full_width_separator",          true);
// user_pref("userChrome.panel.full_width_padding",            true);

// user_pref("userChrome.sidebar.overlap",                     true);

// user_pref("userChrome.icon.disabled",                       true);
// user_pref("userChrome.icon.account_image_to_right",         true);
// user_pref("userChrome.icon.account_label_to_right",         true);
user_pref("userChrome.icon.menu.full",                      true);
// user_pref("userChrome.icon.global_menu.mac",                true);

// -- User Content -------------------------------------------------------------
user_pref("userContent.player.ui.twoline",                  true);

user_pref("userContent.newTab.hidden_logo",                 true);
// user_pref("userContent.newTab.background_image",            true); // Need wallpaper image to `userContent.css`. :root { --uc-newTab-wallpaper: url("../icons/background_image.png"); }

user_pref("userContent.page.proton_color.dark_blue_accent", true);
// user_pref("userContent.page.proton_color.system_accent",    true);
// user_pref("userContent.page.dark_mode.pdf",                 true);
// user_pref("userContent.page.monospace",                     true);

// == Theme Default Settings ===================================================
// -- User Chrome --------------------------------------------------------------
user_pref("userChrome.compatibility.theme",       true);
user_pref("userChrome.compatibility.os",          true);

user_pref("userChrome.theme.built_in_contrast",   true);
user_pref("userChrome.theme.system_default",      true);
user_pref("userChrome.theme.proton_color",        true);
user_pref("userChrome.theme.proton_chrome",       true); // Need proton_color
user_pref("userChrome.theme.fully_color",         true); // Need proton_color
user_pref("userChrome.theme.fully_dark",          true); // Need proton_color

user_pref("userChrome.decoration.cursor",         true);
user_pref("userChrome.decoration.field_border",   true);
user_pref("userChrome.decoration.download_panel", true);
user_pref("userChrome.decoration.animate",        true);

user_pref("userChrome.padding.tabbar_width",      true);
user_pref("userChrome.padding.tabbar_height",     true);
user_pref("userChrome.padding.toolbar_button",    true);
user_pref("userChrome.padding.navbar_width",      true);
user_pref("userChrome.padding.urlbar",            true);
user_pref("userChrome.padding.bookmarkbar",       true);
user_pref("userChrome.padding.infobar",           true);
user_pref("userChrome.padding.menu",              true);
user_pref("userChrome.padding.bookmark_menu",     true);
user_pref("userChrome.padding.global_menubar",    true);
user_pref("userChrome.padding.panel",             true);
user_pref("userChrome.padding.popup_panel",       true);

user_pref("userChrome.tab.multi_selected",        true);
user_pref("userChrome.tab.unloaded",              true);
user_pref("userChrome.tab.letters_cleary",        true);
user_pref("userChrome.tab.close_button_at_hover", true);
user_pref("userChrome.tab.sound_hide_label",      true);
user_pref("userChrome.tab.sound_with_favicons",   true);
user_pref("userChrome.tab.pip",                   true);
user_pref("userChrome.tab.container",             true);
user_pref("userChrome.tab.crashed",               true);

user_pref("userChrome.fullscreen.overlap",        true);
user_pref("userChrome.fullscreen.show_bookmarkbar", true);

user_pref("userChrome.icon.library",              true);
user_pref("userChrome.icon.panel",                true);
user_pref("userChrome.icon.menu",                 true);
user_pref("userChrome.icon.context_menu",         true);
user_pref("userChrome.icon.global_menu",          true);
user_pref("userChrome.icon.global_menubar",       true);
user_pref("userChrome.icon.1-25px_stroke",        true);

// -- User Content -------------------------------------------------------------
user_pref("userContent.player.ui",             true);
user_pref("userContent.player.icon",           true);
user_pref("userContent.player.noaudio",        true);
user_pref("userContent.player.size",           true);
user_pref("userContent.player.click_to_play",  true);
user_pref("userContent.player.animate",        true);

user_pref("userContent.newTab.full_icon",      true);
user_pref("userContent.newTab.animate",        true);
user_pref("userContent.newTab.pocket_to_last", true);
user_pref("userContent.newTab.searchbar",      true);

user_pref("userContent.page.field_border",     true);
user_pref("userContent.page.illustration",     true);
user_pref("userContent.page.proton_color",     true);
user_pref("userContent.page.dark_mode",        true); // Need proton_color
user_pref("userContent.page.proton",           true); // Need proton_color

// ** Useful Options ***********************************************************
// Tab preview
// https://blog.nightly.mozilla.org/2024/02/06/a-preview-of-tab-previews-these-weeks-in-firefox-issue-153/
user_pref("browser.tabs.hoverPreview.enabled", true);

// Paste suggestion at urlbar
// https://blog.nightly.mozilla.org/2023/12/04/url-gonna-want-to-check-this-out-these-weeks-in-firefox-issue-150/
user_pref("browser.urlbar.clipboard.featureGate", true);

// Integrated calculator at urlbar
user_pref("browser.urlbar.suggest.calculator", true);

// Integrated unit convertor at urlbar
// user_pref("browser.urlbar.unitConversion.enabled", true);

// Draw in Titlebar
// user_pref("browser.tabs.drawInTitlebar", true);
// user_pref("browser.tabs.inTitlebar",        1); // Nightly, 96 Above

// Searchbar, Removed from settings starting with FF v122
// user_pref("browser.search.widget.inNavBar",    true);

// Firefox view search
// https://blog.nightly.mozilla.org/2023/12/14/better-searching-in-firefox-to-close-out-2023-these-weeks-in-firefox-issue-151/
// user_pref("browser.firefox-view.search.enabled",       true);
// user_pref("browser.firefox-view.virtual-list.enabled", true);

// Firefox screenshot
// https://blog.nightly.mozilla.org/2024/01/22/happy-new-year-these-weeks-in-firefox-issue-152/
// user_pref("screenshots.browser.component.enabled", true);

// ** Scrolling Settings *******************************************************
// == Only Sharpen Scrolling ===================================================
//         Pref                                             Value      Original
/*
user_pref("mousewheel.min_line_scroll_amount",                 10); //        5
user_pref("general.smoothScroll.mouseWheel.durationMinMS",     80); //       50
user_pref("general.smoothScroll.currentVelocityWeighting", "0.15"); //   "0.25"
user_pref("general.smoothScroll.stopDecelerationWeighting", "0.6"); //    "0.4"
*/

// == Smooth Scrolling ==========================================================
// ** Scrolling Options ********************************************************
// based on natural smooth scrolling v2 by aveyo
// this preset will reset couple extra variables for consistency
//         Pref                                              Value                 Original
/*
user_pref("apz.allow_zooming",                               true);            ///     true
user_pref("apz.force_disable_desktop_zooming_scrollbars",   false);            ///    false
user_pref("apz.paint_skipping.enabled",                      true);            ///     true
user_pref("apz.windows.use_direct_manipulation",             true);            ///     true
user_pref("dom.event.wheel-deltaMode-lines.always-disabled", true);            ///    false
user_pref("general.smoothScroll.currentVelocityWeighting", "0.12");            ///   "0.25" <- 1. If scroll too slow, set to "0.15"
user_pref("general.smoothScroll.durationToIntervalRatio",    1000);            ///      200
user_pref("general.smoothScroll.lines.durationMaxMS",         100);            ///      150
user_pref("general.smoothScroll.lines.durationMinMS",           0);            ///      150
user_pref("general.smoothScroll.mouseWheel.durationMaxMS",    100);            ///      200
user_pref("general.smoothScroll.mouseWheel.durationMinMS",      0);            ///       50
user_pref("general.smoothScroll.mouseWheel.migrationPercent", 100);            ///      100
user_pref("general.smoothScroll.msdPhysics.continuousMotionMaxDeltaMS", 12);   ///      120
user_pref("general.smoothScroll.msdPhysics.enabled",                  true);   ///    false
user_pref("general.smoothScroll.msdPhysics.motionBeginSpringConstant", 200);   ///     1250
user_pref("general.smoothScroll.msdPhysics.regularSpringConstant",     200);   ///     1000
user_pref("general.smoothScroll.msdPhysics.slowdownMinDeltaMS",         10);   ///       12
user_pref("general.smoothScroll.msdPhysics.slowdownMinDeltaRatio",  "1.20");   ///    "1.3"
user_pref("general.smoothScroll.msdPhysics.slowdownSpringConstant",   1000);   ///     2000
user_pref("general.smoothScroll.other.durationMaxMS",         100);            ///      150
user_pref("general.smoothScroll.other.durationMinMS",           0);            ///      150
user_pref("general.smoothScroll.pages.durationMaxMS",         100);            ///      150
user_pref("general.smoothScroll.pages.durationMinMS",           0);            ///      150
user_pref("general.smoothScroll.pixels.durationMaxMS",        100);            ///      150
user_pref("general.smoothScroll.pixels.durationMinMS",          0);            ///      150
user_pref("general.smoothScroll.scrollbars.durationMaxMS",    100);            ///      150
user_pref("general.smoothScroll.scrollbars.durationMinMS",      0);            ///      150
user_pref("general.smoothScroll.stopDecelerationWeighting", "0.6");            ///    "0.4"
user_pref("layers.async-pan-zoom.enabled",                   true);            ///     true
user_pref("layout.css.scroll-behavior.spring-constant",   "250.0");            ///   "250.0"
user_pref("mousewheel.acceleration.factor",                     3);            ///       10
user_pref("mousewheel.acceleration.start",                     -1);            ///       -1
user_pref("mousewheel.default.delta_multiplier_x",            100);            ///      100
user_pref("mousewheel.default.delta_multiplier_y",            100);            ///      100
user_pref("mousewheel.default.delta_multiplier_z",            100);            ///      100
user_pref("mousewheel.min_line_scroll_amount",                  0);            ///        5
user_pref("mousewheel.system_scroll_override.enabled",       true);            ///     true <- 2. If scroll too fast, set to false
user_pref("mousewheel.system_scroll_override_on_root_content.enabled", false); ///     true
user_pref("mousewheel.transaction.timeout",                  1500);            ///     1500
user_pref("toolkit.scrollbox.horizontalScrollDistance",         4);            ///        5
user_pref("toolkit.scrollbox.verticalScrollDistance",           3);            ///        3
*/

Additional context

Some devs figured solution.
You can see what changed in this commit.

Temporal solution:
After adding code below to userChrome.css multirow works.

@-moz-document url(chrome://browser/content/browser.xhtml) {
	scrollbox[part][orient="horizontal"] {
		> * {
			flex-wrap: wrap;
			/* Fix for Firefox 131 */
		}
	}
}