Slightly better patch.

browser/components/prefwindow/content/pref.xul

@@ -116,7 +116,7 @@
     var button = prefsCategories.childNodes[lastPanel];
     document.getElementById("panelFrame").setAttribute("src", button.getAttribute("url"));
     button.focus();
-    button.click();
+    button.checked = true;
   ]]>
   </script>