* properly set for EnterNotify and LeaveNotify
* events except window, subwindow, x, y,
* detail, and same_screen. (x_root and y_root
* must be valid, even though x and y needn't
* be valid). */
* properly set for EnterNotify and LeaveNotify
* events except window, subwindow, x, y,
* detail, and same_screen. (x_root and y_root
* must be valid, even though x and y needn't
* be valid). */