Draw on/directly above desktop?

Is there a way to force a window directly above the desktop and make it transparent? Basically I want a way to draw an image and animation on the desktop so that it integrates (ie. a clock that sits on your desktop, below other windows, has a transp开发者_如何转开发arent background, etc).

Also, if you have a solution, is it an official API?

Use an NSWindow initialised with style NSBorderlessWindowMask and make it floating

setLevel:NSFloatingWindowLevel

You can place your view hierarchy into that window.