assert(w != nullptr);

	if (_game_mode != GM_MENU) {

		Viewport *vp = w->viewport;

		if ((in && vp->zoom <= _settings_client.gui.zoom_min) || (!in && vp->zoom >= _settings_client.gui.zoom_max)) return;

		Point pt = GetTileZoomCenterWindow(in, w);

		if (pt.x != -1) {

			ScrollWindowTo(pt.x, pt.y, -1, w, true);

			DoZoomInOutWindow(in ? ZOOM_IN : ZOOM_OUT, w);

		}

	}

}

void FixTitleGameZoom(int zoom_adjust)

{

	if (_game_mode != GM_MENU) return;

	Viewport *vp = FindWindowByClass(WC_MAIN_WINDOW)->viewport;

	/* Adjust the zoom in/out.

	 * Can't simply add, since operator+ is not defined on the ZoomLevel type. */

	vp->zoom = _gui_zoom;

		vp->zoom--;

		zoom_adjust++;

	}

		vp->zoom++;

		zoom_adjust--;

	}

	vp->virtual_width = ScaleByZoom(vp->width, vp->zoom);

	vp->virtual_height = ScaleByZoom(vp->height, vp->zoom);

}

static const struct NWidgetPart _nested_main_window_widgets[] = {

	NWidget(NWID_VIEWPORT, INVALID_COLOUR, WID_M_VIEWPORT), SetResize(1, 1),

};

enum {

	GHK_QUIT,

	GHK_ABANDON,

	GHK_CONSOLE,

	GHK_BOUNDING_BOXES,

	GHK_DIRTY_BLOCKS,

	GHK_CENTER,

	GHK_CENTER_ZOOM,

	GHK_RESET_OBJECT_TO_PLACE,

	GHK_DELETE_WINDOWS,

	GHK_DELETE_NONVITAL_WINDOWS,

	GHK_DELETE_ALL_MESSAGES,