A well-known disadvantage of stacking is that when windows are painted over each other, they actually end up erasing the previous contents of whatever part of the screen they are covering. Those windows must be redrawn when they are brought to the foreground, or when visible parts of them change. When a window has changed or when its position on the screen has changed, the window manager will detect this and may re-stack all windows, requiring that each window redraw itself, and pass its new appearance along to the window manager before it is drawn. When an application stops responding, it may be unable to redraw itself, which sometimes causes the area within the window frame to retain images of other windows when it is brought to the foreground. This problem is commonly seen on Windows XP and earlier, as well as some X window managers.