Protection against more than one instance of UI

SystemEventHandler.js

@@ -119,6 +119,10 @@ function newSystemEventHandler () {
         }
       }
     }
+
+    if (thisObject.isConnected() !== true) {
+      canvas.cockpitSpace.setStatus('Lost connection with the local backend. Please check that all localhost servers are running.', 100, canvas.cockpitSpace.statusTypes.WARNING)
+    }
   }
 
   function setuptWebSockets (callBackFunction) {