diff --git a/src/window_gui.h b/src/window_gui.h
--- a/src/window_gui.h
+++ b/src/window_gui.h
@@ -651,9 +651,9 @@ public:
 	/**
 	 * Some data on this window has become invalid.
 	 * @param data information about the changed data.
+	 * @param gui_scope Whether the call is done from GUI scope. You may not do everything when not in GUI scope. See #InvalidateWindowData() for details.
 	 */
-	virtual void OnInvalidateData(int data = 0) {}
-
+	virtual void OnInvalidateData(int data = 0, bool gui_scope = true) {}
 
 	/**
 	 * The user clicked some place on the map when a tile highlight mode