--- a/dom/xbl/nsXBLWindowKeyHandler.cpp
+++ b/dom/xbl/nsXBLWindowKeyHandler.cpp
@@ -560,19 +560,22 @@ nsXBLWindowKeyHandler::HandleEventOnCapt
 void
 nsXBLWindowKeyHandler::HandleEventOnCaptureInSystemEventGroup(
                          KeyboardEvent* aEvent)
 {
   WidgetKeyboardEvent* widgetEvent =
     aEvent->WidgetEventPtr()->AsKeyboardEvent();
 
   // If the event won't be sent to remote process, this listener needs to do
-  // nothing.
-  if (widgetEvent->mFlags.mOnlySystemGroupDispatchInContent ||
-      !widgetEvent->WillBeSentToRemoteProcess()) {
+  // nothing.  Note that even if mOnlySystemGroupDispatchInContent is true,
+  // we need to send the event to remote process and check reply event
+  // before matching it with registered shortcut keys because event listeners
+  // in the system event group may want to handle the event before registered
+  // shortcut key handlers.
+  if (!widgetEvent->WillBeSentToRemoteProcess()) {
     return;
   }
 
   if (!HasHandlerForEvent(aEvent)) {
     return;
   }
 
   // If this event wasn't marked as IsCrossProcessForwardingStopped,