--- a/mobile/android/components/PromptService.js
+++ b/mobile/android/components/PromptService.js
@@ -756,17 +756,19 @@ let PromptUtils = {
 
   fireDialogEvent: function(aDomWin, aEventName) {
     // accessing the document object can throw if this window no longer exists. See bug 789888.
     try {
       if (!aDomWin.document)
         return;
       let event = aDomWin.document.createEvent("Events");
       event.initEvent(aEventName, true, true);
-      aDomWin.dispatchEvent(event);
+      let winUtils = aDomWin.QueryInterface(Ci.nsIInterfaceRequestor)
+                           .getInterface(Ci.nsIDOMWindowUtils);
+      winUtils.dispatchEventToChromeOnly(aDomWin, event);
     } catch(ex) {
     }
   }
 };
 
 XPCOMUtils.defineLazyGetter(PromptUtils, "passwdBundle", function () {
   return Services.strings.createBundle("chrome://passwordmgr/locale/passwordmgr.properties");
 });