diff -up mozilla-aurora/browser/app/profile/firefox.js.addons mozilla-aurora/browser/app/profile/firefox.js
--- mozilla-aurora/browser/app/profile/firefox.js.addons	2014-05-06 13:17:13.000000000 +0200
+++ mozilla-aurora/browser/app/profile/firefox.js	2014-05-06 14:16:32.678968008 +0200
@@ -65,7 +65,8 @@ pref("extensions.hotfix.certs.1.sha1Fing
 
 // Disable add-ons that are not installed by the user in all scopes by default.
 // See the SCOPE constants in AddonManager.jsm for values to use here.
-pref("extensions.autoDisableScopes", 15);
+pref("extensions.autoDisableScopes", 0);
+pref("extensions.showMismatchUI", false);
 
 // Dictionary download preference
 pref("browser.dictionaries.download.url", "https://addons.mozilla.org/%LOCALE%/firefox/dictionaries/");
diff -up mozilla-aurora/toolkit/mozapps/extensions/internal/XPIProvider.jsm.addons mozilla-aurora/toolkit/mozapps/extensions/internal/XPIProvider.jsm
--- mozilla-aurora/toolkit/mozapps/extensions/internal/XPIProvider.jsm.addons	2014-05-06 14:16:32.680968014 +0200
+++ mozilla-aurora/toolkit/mozapps/extensions/internal/XPIProvider.jsm	2014-05-06 14:17:29.482132549 +0200
@@ -1894,7 +1894,7 @@ this.XPIProvider = {
         this.showUpgradeUI();
         flushCaches = true;
       }
-      else if (aAppChanged === undefined) {
+      else {
         // For new profiles we will never need to show the add-on selection UI
         Services.prefs.setBoolPref(PREF_SHOWN_SELECTION_UI, true);
       }