 <p>You´ll want to use NSWindowLevel, in specific kCGDesktopWindowLevel. A short overview on NSWindowLevel can be found <a href="http://cocoadev.com/index.pl?NSWindowLevel" rel="nofollow">here</a>, and a <a href="http://stackoverflow.com/questions/4982584/how-do-i-draw-the-desktop-on-mac-os-x/4987525#4987525">more elaborate solution</a> has been posted to a <a href="http://stackoverflow.com/questions/4982584/how-do-i-draw-the-desktop-on-mac-os-x">similar stackoverflow question</a> before.</p>