// Begin drag. hotspot is the location of the drag position relative to the upper-left
// corner of the image. This is full screen only. fullScreenRect gives the
// position of the window on the screen, to restrict the drag to.
// Begin drag. hotspot is the location of the drag position relative to the upper-left
// corner of the image. This is full screen only. fullScreenRect gives the
// position of the window on the screen, to restrict the drag to.