Title bar color change delay on window focus gain

[DreamC]

Describe the bug
Windows with a lot of tabs have a significant delay for changing color of title bar to accent color. This mostly happens when Firefox window is completely hidden behind any other application window. If it's visible at least partially, then the delay is not that noticeable.
It also seems to affect general focus gain event, i.e. Github text input will be highlighted at the same time the title bar is painted.
Without Lepton (default Firefox UI), there is almost no delay in any case.

Expected behavior
Color is expected to change the moment a window gains focus disregarding the number of tabs in it.

Screenshots

wmGJvg5.-.Imgur.mp4

• Fallback: https://imgur.com/a/pUkT9Ia

Environment:

• Distribution
  • Original Lepton
  • Lepton's photon style
  • Lepton's proton style
• Firefox Version: 105.0
• OS:
  • Linux
  • Windows
  • Mac
  • Other:
• Theme:
  • Light
  • Dark
  • Alpenglow (System: Light)
  • Alpenglow (System: Dark)
  • System Default
    • GTK Theme Name (Linux only):
  • Other: (e.g. Photon Colors, Google Chrome Dark, Fairytale Of Nature)

user.js setup: Default

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

// Proton Enabled #127 || Removed at 97 #328 (Maintained for compatibility with ESR)
user_pref("browser.proton.enabled", true);

// Proton Tooltip
user_pref("browser.proton.places-tooltip.enabled", true);

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

// CSS Color Mix - 88 Above
user_pref("layout.css.color-mix.enabled", true);

// CSS Blur Filter - 88 Above
user_pref("layout.css.backdrop-filter.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_separtor",           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.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
user_pref("userChrome.icon.panel_sparse",             false); // Just option

// 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);

// == 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_seperator

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

// == Theme Custom Settings ====================================================
// -- User Chrome --------------------------------------------------------------
// user_pref("userChrome.theme.proton_color.dark_blue_accent", true);
// user_pref("userChrome.theme.monospace",                     true);

// user_pref("userChrome.decoration.disable_panel_animate",    true);
// user_pref("userChrome.decoration.disable_sidebar_animate",  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.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.sidebar_header",               true);
// user_pref("userChrome.hidden.sidebar_header.vertical_tab_only", true);
// user_pref("userChrome.hidden.urlbar_iconbox",               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.rounding.square_button",              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_field",               true);
// user_pref("userChrome.rounding.square_checklabel",          true);

// user_pref("userChrome.padding.first_tab",                   true);
// user_pref("userChrome.padding.drag_space",                  true);
// user_pref("userChrome.padding.drag_space.maximized",        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.urlView.move_icon_to_left",           true);
// user_pref("userChrome.urlView.go_button_when_typing",       true);
// user_pref("userChrome.urlView.always_show_page_actions",    true);

// user_pref("userChrome.tabbar.as_titlebar",                  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.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.sound_show_label",                true); // Need remove sound_hide_label

// 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.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.page.proton_color.dark_blue_accent", true);
// user_pref("userContent.page.proton_color.system_accent",    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 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.field_border",   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.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 ***********************************************************
// 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

// ** 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 Scroling ==========================================================
// ** 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

[DreamC]

In addition to what was said before, it's not just the delay to color tabbar.
It also affects selecting Firefox window after minimizing it - click on the taskbar and after this same delay Firefox will come into focus (with colored tabbar).
It may sometimes as well cause pages to redraw after a delay when you give focus to Firefox. Will try to capture a video of that.

[black7375]

This should have been improved in v8.6.0.