GETWINDOWS: Retrieve the current graphics window.
            IDLgrWindow: An on-screen area on a display device.
            WDELETE Procedure: Delete Direct Graphics windows.
            WIDGET_WINDOW: Create a graphics widget.
            WINDOW: Create an empty graphics window.
            WINDOW Procedure: Create a Direct Graphics window.
            WSET: Select the current Direct Graphics window.
            WSHOW: Expose or hide a Direct Graphics window.