xsetaction [, action, window]
[x11] Sets the copy action associated with the window.
window defaults to
1. Choose what to replace the destination with by selecting
Note that actions 1 and 2 are reversible. These are suitable for display of sprites: objects that change the image but may be removed without a trace by drawing them again. i use them for simultaneous display of multiple pseudo-cursors.
See also: xtv, !window