Wanted: 2d pop up menus (color palette pop ups)

[Repenning Alexander <ralex@tigger.cs.colorado.edu>]

I'm looking for ways, no any way really, to implement two dimmensional
pop up menus. I am especially interested in 2D color palette pop ups
like the ones used in many applications dealing with the interactive
change of the pen color, e.g., ResEdit's (cicn editor). Linear menus
are limited when dealing with a large number of items. A linear color
palette pop up with 256 items would be rather tedious for users, so I
believe 2d pop up menus would be a nice extension to MCL.

MCL supports linear menus really great but I don't quite see how I
should implement 2d pop ups. Any pointers and hints are very much
appreciated..

   Alex