Fix f6d5c01: Delay deletion when closing windows

src/waypoint_gui.cpp

@@ -74,9 +74,10 @@ public:
 		this->OnInvalidateData(0);
 	}
 
-	~WaypointWindow()
+	void Close() override
 	{
 		DeleteWindowById(GetWindowClassForVehicleType(this->vt), VehicleListIdentifier(VL_STATION_LIST, this->vt, this->owner, this->window_number).Pack(), false);
+		this->Window::Close();
 	}
 
 	void SetStringParameters(int widget) const override