It would be nice if ...
Menu items (direct character action or not) that will not work when placed on a action-bar slot:
1) Would fail placement when trying to drop it in a action-bar slot. (or block dragging them)
Or
2) Would just work when placed in a action-bar slot.
Like for example: "(Adventure,) Toggles", or "(Adventure, Toggles,) Display Mine Support Radii".
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(Mmm, relative new shortcut keys feature might have something to do with this.)