What's under the mouse?

Is there a good mechanism in RhinoCommon to identify the piece of geometry currently under the mouse cursor? that is to say - the piece of geometry that would be selected if the user were to click (but without actually clicking). Or better yet, a Point3d in space projected to the first object under the user’s cursor.

got what I needed from this GH script by Vicente Soler: http://www.grasshopper3d.com/forum/topics/mouse-coord?commentId=2985220%3AComment%3A925353