Regression fix: Undo can be used again with color picker up

I introduced a bug when I deployed Hotkeys for palette colors, whoops!

You should be able to hit Ctrl+Z (or any of the other bindings for Undo) when the color picker is up. This has worked for awhile, unfortunately I broke this behavior in Hotkeys for palette colors.

I just deployed a fix for this, so undo now works again when the color picker is shown.