How can i get background tranparency ?

hi, i want to get a game with background transparency like in this site but i don't know how to do it, i was looking for in internet, but not success.

Thanks

It's only usable with dashboard widgets, sorry

sorry but tis feature is only supported for mac osx dashboard widgets now. you might be able to make the hole window transparent with an api. also you can change the shape of the window in windows using a bitmap maks that you can create in unity with a shader but these things might become heavy. i don't know much about macs. you can find many code example for those apis in google easily.