Add dialog-open event (#6748)

program/js/app.js

@@ -8160,7 +8160,9 @@ function rcube_webmail()
     });
 
     // Don't propagate keyboard events to the UI below the dialog (#6055)
-    popup.parent().on('keydown keyup', function(e) { e.stopPropagation(); });
+    dialog.on('keydown keyup', function(e) { e.stopPropagation(); });
+
+    this.triggerEvent('dialog-open', {obj: popup});
 
     return popup;
   };