diff --git a/src/querystring_gui.h b/src/querystring_gui.h
--- a/src/querystring_gui.h
+++ b/src/querystring_gui.h
@@ -67,6 +67,7 @@ struct QueryStringBaseWindow : public Wi
 	void DrawEditBox(int wid);
 	void HandleEditBox(int wid);
 	int HandleEditBoxKey(int wid, uint16 key, uint16 keycode, EventState &state);
+	virtual void OnOpenOSKWindow(int wid);
 };
 
 void ShowOnScreenKeyboard(QueryStringBaseWindow *parent, int button, int cancel, int ok);