Force Quit required after changing default font

[enkidu_jones]

I'm experiencing a rather odd problem: if I go into Preferences, General, and then change the selected value under "Default fonts" in the "for" section (for example, change it from "Bibliographies" to "References"), I cannot quit Bookends—I have to do Force Quit. Everything else continues to operate correctly, it seems I just cannot Quit!

This seems to have started when I upgraded to 10.9 Mavericks. Is anyone else able to reproduce this, or is it just me?

Thanks!

[corrado33]

I'm running bookends 12.1.1 and OS X 10.9.1 and I can quit just fine after changing those things. No force quit required.