Method OnResize

src/viewport_gui.cpp:106–112

	}

	void OnResize() override
	{
		if (this->viewport != nullptr) {
			NWidgetViewport *nvp = this->GetWidget<NWidgetViewport>(WID_EV_VIEWPORT);
			nvp->UpdateViewportCoordinates(this);
		}
	}

	void OnScroll(Point delta) override
	{