Cocoa transparent window?

[msp]

Hi,

anyone knows how to create a window like this?
I looks like transparent and round shaped window?
I'm new to cocoa development and curious if someone could point me to an example that creates something like this.

 

[robbieduncan]

http://developer.apple.com/samplecode/FunkyOverlayWindow/FunkyOverlayWindow.html

edit : also http://developer.apple.com/samplecode/RoundTransparentWindow/RoundTransparentWindow.html

The Apple Developer website is actually helpfull!