VoiceOver reads an AXValue for a pop-up button - that is the selected
item. But button's title does not set an AXValue, as it probably is
not a menu item. So change the code set to the title by setting a
single menu item with that title.

This fixes accessibility of the pop-up when accessing its value before
it is first popped up. It makes the code consistent with setGrammarName:
which works fine (that's how I discovered how to fix it).

This fixes semantics of the button and thus also its
accessibility. The macro recording button represents state - more
specifically a boolean state, so it has to be a NSToggleButton (or
its specialization). Then the button is presented to the VoiceOver
user as an AXCheckbox - that is a checkbox with on and off value -
which is exactly what the button's function is. Examples of this in
system apps is e.g. the "Play" button in QuickTime Player, which is
also an AXCheckbox ("Pause" is then simply an unchecked "Play"
checkbox).