Invoke zoom changed handler to apply the zoom factor

Author: UrbanBobek

app/display/runtime/src/main/java/org/csstudio/display/builder/runtime/app/ZoomAction.java

@@ -49,6 +49,8 @@ public ZoomAction(final DisplayRuntimeInstance instance)
         {
             String zoom = String.format("%d %%", default_zoom_factor);
             setValue(zoom);
+            // Invoke zoom changed handler
+            getOnAction().handle(null);
         });
     }