From 2ce8b3b74e4f3576a067c7ff9a730775b13d36e7 Mon Sep 17 00:00:00 2001
From: wolfbeast <mcwerewolf@gmail.com>
Date: Sat, 22 Jul 2017 01:53:42 +0200
Subject: [PATCH] Add a signal preference for dynamic color changes to adjust
 "brighttext" in the front-end.

This makes all relevant toolbars pick up the fact that the Windows accent color has changed and should check and if necessary update the "brighttext" property on them for styling of controls.
This is a bit of a hack-around to the fact that there is no real easy way otherwise to notify the front-end of color changes without needing a change in focus of the window.
There is a deliberate 300ms delay built in, because otherwise the styles might not have propagated yet, resulting in brighttext not being updated properly.
---
 browser/base/content/browser.js | 17 +++++++++++++++++
 widget/windows/nsWindow.cpp     |  2 ++
 2 files changed, 19 insertions(+)

diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index d813a55cc8..bbfef0049b 100644
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -8075,6 +8075,7 @@ var ToolbarIconColor = {
     window.addEventListener("activate", this);
     window.addEventListener("deactivate", this);
     Services.obs.addObserver(this, "lightweight-theme-styling-update", false);
+    gPrefService.addObserver("ui.colorChanged", this, false);
 
     // If the window isn't active now, we assume that it has never been active
     // before and will soon become active such that inferFromText will be
@@ -8089,6 +8090,7 @@ var ToolbarIconColor = {
     window.removeEventListener("activate", this);
     window.removeEventListener("deactivate", this);
     Services.obs.removeObserver(this, "lightweight-theme-styling-update");
+    gPrefService.removeObserver("ui.colorChanged", this);
   },
 
   handleEvent: function (event) {
@@ -8107,6 +8109,18 @@ var ToolbarIconColor = {
         // lightweight-theme-styling-update observer.
         setTimeout(() => { this.inferFromText(); }, 0);
         break;
+      case "nsPref:changed":
+        // system color change
+        var colorChangedPref = false;
+        try {
+          colorChangedPref = gPrefService.getBoolPref("ui.colorChanged");
+        } catch(e) { }
+        // if pref indicates change, call inferFromText() on a small delay
+        if (colorChangedPref == true)
+          setTimeout(() => { this.inferFromText(); }, 300);
+        break;
+      default:
+        console.error("ToolbarIconColor: Uncaught topic " + aTopic);
     }
   },
 
@@ -8140,6 +8154,9 @@ var ToolbarIconColor = {
       else
         toolbar.setAttribute("brighttext", "true");
     }
+    
+    // Clear pref if set, since we're done applying the color changes.
+    gPrefService.clearUserPref("ui.colorChanged");
   }
 }
 
diff --git a/widget/windows/nsWindow.cpp b/widget/windows/nsWindow.cpp
index e721267ba1..a8923f78e3 100644
--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -7141,8 +7141,10 @@ nsWindow::OnSysColorChanged()
     NotifySysColorChanged();
     // On Windows 10 only, we trigger a theme change to pick up changed media
     // queries that are needed for accent color changes.
+    // We also set a temp pref to notify the FE that the colors have changed.
     if (IsWin10OrLater()) {
       NotifyThemeChanged();
+      Preferences::SetBool("ui.colorChanged", true);
     }
   }
 }