Unsolved Toolbutton/Button that resembles the Excel/Word text color selector buttons

[Trilec]

Hi all,
I would like to develop a toolbutton/Button that resembles the Excel/Word text color selector button
Any recommendations as to the approach or has someone done one already and is ok to post.
My feeling is a simple style hack ,checking for toolButtonFollowStyle or DownArrow (or other) is selected to trigger the style, then no subclass is necessary.
ie: redraw the colour background below an icon as a small rectangle