Detect 2D under mouse and overlapping buttons mouse-overs

Hello there,

I have multiple GUI scripts spread across multiple GOs. In addition to that I also have a central (3D) picking script.

I have two questions:

a) How can I globally detect that a 2D GUI element is under the mouse so I won’t do then any raycasting into the 3d scene for picking?

b) if I draw buttons over each other (overlapping GUI elements) it looks like even though the depth is not the same, each one gets mouse(-over?) events instead of only the top-most GUI layer. If that observation correct, how do you handle that?

thx
Dom

sorry for a) - it’s a known issue:

http://forum.unity3d.com/viewtopic.php?t=8230
http://forum.unity3d.com/viewtopic.php?t=8012

I guess the same for b)?