--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -3660,16 +3660,19 @@ nsWindow::Create(nsIWidget* aParent,
 
         bool useAlphaVisual = (mWindowType == eWindowType_popup &&
                                aInitData->mSupportTranslucency);
 
         // mozilla.widget.use-argb-visuals is a hidden pref defaulting to false
         // to allow experimentation
         if (Preferences::GetBool("mozilla.widget.use-argb-visuals", false))
             useAlphaVisual = true;
+        else if (useAlphaVisual &&
+                 Preferences::GetBool("mozilla.widget.gtk.force-disable-argb-visuals", false))
+            useAlphaVisual = false;
 
         // We need to select an ARGB visual here instead of in
         // SetTransparencyMode() because it has to be done before the
         // widget is realized.  An ARGB visual is only useful if we
         // are on a compositing window manager.
         if (useAlphaVisual) {
             GdkScreen *screen = gtk_widget_get_screen(mShell);
             if (gdk_screen_is_composited(screen)) {