For fun I created a "poor man's" keyboard navigation for the floating menus. 
Assumed the menu is built vertically.
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A shortcut opens the menu and moves the mouse to the first button.
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"k" moves the mouse down one button. "j" moves the mouse one button up. If you need it, activate key repeat.
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Enter (or Space), triggers the macro of the highlighted button and closes the menu.
This just needs a CAG to set the actions of "k", "j" and Enter when the floating menu is open.