Do buttons "bounds" have to be boxes?

[Knox]

I'm not sure if this has been answered before, but is there a "simple" way to make it so buttons only detect where the mouse is based on its alpha channel? I'm making buttons go around a circle and right now the button's over graphic will highlight when the mouse is over the whole graphic (because obviously the sprite is a box shape)...but I don't want the mouse to activate the button's over or pressed graphics if the mouse is over the transparent part of the button (which is outside of the gui, which is a circle).

Does this make sense?

**Pixel Perfect Detection is set to true**

EDIT:

Ok looks like gui button click detections are always rectangular...

Found this as a work-around...http://www.adventuregamestudio.co.uk/forums/index.php?topic=28882.msg367578#msg367578

Hopefully this feature could be added sometime soon?