diff --git a/browser/base/content/utilityOverlay.js b/browser/base/content/utilityOverlay.js
index 65fe3d598401..6d9e6158ae81 100644
--- a/browser/base/content/utilityOverlay.js
+++ b/browser/base/content/utilityOverlay.js
@@ -505,10 +505,13 @@ function openPreferences(paneID, extraArgs)
     }
 
     if (newLoad) {
-      browser.addEventListener("load", function onload() {
-        browser.removeEventListener("load", onload, true);
+      Services.obs.addObserver(function advancedPaneLoadedObs(prefWin, topic, data) {
+        if (prefWin != browser.contentWindow) {
+          return;
+        }
+        Services.obs.removeObserver(advancedPaneLoadedObs, "advanced-pane-loaded");
         switchToPane();
-      }, true);
+      }, "advanced-pane-loaded", false);
     } else {
       switchToPane();
     }
diff --git a/browser/components/preferences/in-content/advanced.js b/browser/components/preferences/in-content/advanced.js
index db1e13bb10be..b236029f46be 100644
--- a/browser/components/preferences/in-content/advanced.js
+++ b/browser/components/preferences/in-content/advanced.js
@@ -71,6 +71,9 @@ var gAdvancedPane = {
 #endif
     this.updateActualCacheSize();
     this.updateActualAppCacheSize();
+
+    // Notify observers that the UI is now ready
+    Services.obs.notifyObservers(window, "advanced-pane-loaded", null);
   },
 
   /**
diff --git a/browser/components/preferences/in-content/preferences.js b/browser/components/preferences/in-content/preferences.js
index 80a6058e40af..8c877a19d848 100644
--- a/browser/components/preferences/in-content/preferences.js
+++ b/browser/components/preferences/in-content/preferences.js
@@ -44,6 +44,7 @@ function selectCategory(name) {
   let categories = document.getElementById("categories");
   let item = categories.querySelector(".category[value=" + name + "]");
   categories.selectedItem = item;
+  gotoPref(name);
 }
 
 function gotoPref(page) {
diff --git a/toolkit/mozapps/extensions/test/browser/browser_experiments.js b/toolkit/mozapps/extensions/test/browser/browser_experiments.js
index 453d9910170f..76c4a546b508 100644
--- a/toolkit/mozapps/extensions/test/browser/browser_experiments.js
+++ b/toolkit/mozapps/extensions/test/browser/browser_experiments.js
@@ -185,17 +185,17 @@ add_task(function* testOpenPreferences() {
   let deferred = Promise.defer();
   Services.obs.addObserver(function observer(prefWin, topic, data) {
     Services.obs.removeObserver(observer, "advanced-pane-loaded");
-
     info("Advanced preference pane opened.");
+    executeSoon(function() {
+      // We want this test to fail if the preferences pane changes.
+      let el = prefWin.document.getElementById("dataChoicesPanel");
+      is_element_visible(el);
 
-    // We want this test to fail if the preferences pane changes.
-    let el = prefWin.document.getElementById("dataChoicesPanel");
-    is_element_visible(el);
+      prefWin.close();
+      info("Closed preferences pane.");
 
-    prefWin.close();
-    info("Closed preferences pane.");
-
-    deferred.resolve();
+      deferred.resolve();
+    });
   }, "advanced-pane-loaded", false);
 
   info("Loading preferences pane.");
diff --git a/toolkit/mozapps/extensions/test/browser/head.js b/toolkit/mozapps/extensions/test/browser/head.js
index 1181d99a3005..2a95d4799a81 100644
--- a/toolkit/mozapps/extensions/test/browser/head.js
+++ b/toolkit/mozapps/extensions/test/browser/head.js
@@ -432,12 +432,12 @@ function is_hidden(aElement) {
 
 function is_element_visible(aElement, aMsg) {
   isnot(aElement, null, "Element should not be null, when checking visibility");
-  ok(!is_hidden(aElement), aMsg);
+  ok(!is_hidden(aElement), aMsg || (aElement + " should be visible"));
 }
 
 function is_element_hidden(aElement, aMsg) {
   isnot(aElement, null, "Element should not be null, when checking visibility");
-  ok(is_hidden(aElement), aMsg);
+  ok(is_hidden(aElement), aMsg || (aElement + " should be hidden"));
 }
 
 /**