# HG changeset patch
# User Nicolas Silva <nsilva@mozilla.com>
# Parent  14c5bf11d37b9e92d27f7089d9392de2ac339bb3
Bug 1272332 - Allow gtk the global dark theme behind a pref. r=karlt

diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -4560,16 +4560,17 @@ pref("gfx.content.use-native-pushlayer",
 #ifdef ANDROID
 pref("gfx.apitrace.enabled",false);
 #endif
 
 #ifdef MOZ_X11
 pref("gfx.content.use-native-pushlayer", true);
 #ifdef MOZ_WIDGET_GTK
 pref("gfx.xrender.enabled",false);
+pref("widget.allow-gtk-dark-theme", false);
 #endif
 #endif
 
 #ifdef XP_WIN
 pref("gfx.content.use-native-pushlayer", true);
 
 // Whether to disable the automatic detection and use of direct2d.
 pref("gfx.direct2d.disabled", false);
diff --git a/widget/gtk/nsLookAndFeel.cpp b/widget/gtk/nsLookAndFeel.cpp
--- a/widget/gtk/nsLookAndFeel.cpp
+++ b/widget/gtk/nsLookAndFeel.cpp
@@ -1093,26 +1093,32 @@ nsLookAndFeel::Init()
     GdkRGBA color;
     GtkStyleContext *style;
 
     // Gtk manages a screen's CSS in the settings object so we
     // ask Gtk to create it explicitly. Otherwise we may end up
     // with wrong color theme, see Bug 972382
     GtkSettings *settings = gtk_settings_get_for_screen(gdk_screen_get_default());
 
-    // Disable dark theme because it interacts poorly with widget styling in
-    // web content (see bug 1216658).
-    // To avoid triggering reload of theme settings unnecessarily, only set the
-    // setting when necessary.
-    const gchar* dark_setting = "gtk-application-prefer-dark-theme";
-    gboolean dark;
-    g_object_get(settings, dark_setting, &dark, nullptr);
 
-    if (dark) {
-        g_object_set(settings, dark_setting, FALSE, nullptr);
+    bool isContentProcess = XRE_IsContentProcess();
+    bool allowDarkTheme = mozilla::Preferences::GetBool("widget.allow-gtk-dark-theme", false);
+
+    if (isContentProcess || !allowDarkTheme) {
+        // Disable dark theme because it interacts poorly with widget styling in
+        // web content (see bug 1216658).
+        // To avoid triggering reload of theme settings unnecessarily, only set the
+        // setting when necessary.
+        const gchar* dark_setting = "gtk-application-prefer-dark-theme";
+        gboolean dark;
+        g_object_get(settings, dark_setting, &dark, nullptr);
+
+        if (dark) {
+            g_object_set(settings, dark_setting, FALSE, nullptr);
+        }
     }
 
     GtkWidgetPath *path = gtk_widget_path_new();
     gtk_widget_path_append_type(path, GTK_TYPE_WINDOW);
 
     mBackgroundStyle = create_context(path);
     gtk_style_context_add_class(mBackgroundStyle, GTK_STYLE_CLASS_BACKGROUND);