Make OakPasteboardSelector accessible

[dusek]

Issues remaining:

• VoiceOver for some reason cannot track keyboard focus
  (i.e. moving down the list with just down arrow does not move
  VoiceOver cursor). User has to move the VO cursor instead using VO-down
  (and keyboard cursor follows in this case)
• the pasteboard window isn't focused automatically for VoiceOver, user
  has to switch manually to it using VO-F2-F2

Released to public domain by my employer, BRAILCOM,o.p.s.

[sorbits]

Thanks, pulled as 7d47dd2.

Minor change to formatting.

The issues you describe are likely caused by using a custom event loop. I’ve long been meaning to redo the pop-up to be more of a real window since I also want the user to be able to filter the list, so the issue may solve itself (given enough time :) ).