Full windows transparency ?

Hi guys:

Could anyone tell me if this is possible, and, if so, point me how to do it ?

I have seen software that, rolling mouse wheel over the titlebar, changed transparency level. That is very cool and useful and, since Windowblinds can change transparency levels on Windows7 Interface, I thought that maybe this could be done too. In case you can´t, I would suggest it for future feature additions if possible.

Thanks a lot.