Transparency borders / how to ? like this

[macfr]

How is it possible to add a cool transparency effect to the OSX Parallels app borders ?
Like the pict in this thread (middle) : http://panoguide.com/forums/tipsntricks/2039/ or in the guy's links
...hidden options / hack ?

thks
Mfr

 

[honamos]

It's not possible

 

[macfr]

oh :-(
so it's a hack or a fake ?