About MuseScore and About MusicXML aren't on top

1. 'MuseScore'>'About MuseScore' or 'About MusicXML'.

Desired result: Until it is clicked away, the box should always be on top and nothing else clickable within MuseScore.
Actual result: I'm able to click elsewhere in MuseScore - the box is hidden behind MuseScore.

Discussion: 'About Qt' behaves like the desired result.

Using MuseScore 2.0 Nightly Build (5637) - Mac 10.7.4.