diff --git a/xulrunner/app/xulrunner.js b/xulrunner/app/xulrunner.js
index b6d5a0c7a232..d0ffc62a1b4b 100644
--- a/xulrunner/app/xulrunner.js
+++ b/xulrunner/app/xulrunner.js
@@ -60,3 +60,13 @@ pref("xpinstall.dialog.progress.skin", "chrome://mozapps/content/extensions/exte
 pref("xpinstall.dialog.progress.type.chrome", "Extension:Manager");
 pref("xpinstall.dialog.progress.type.skin", "Extension:Manager");
 pref("xpinstall.enabled", true);
+#ifdef XP_WIN
+pref("browser.preferences.instantApply", false);
+#else
+pref("browser.preferences.instantApply", true);
+#endif
+#ifdef XP_MACOSX
+pref("browser.preferences.animateFadeIn", true);
+#else
+pref("browser.preferences.animateFadeIn", false);
+#endif