1. Create a new score for a treble-clef instrument
2. Press "N" to begin Note Entry mode
3. Select quarter-note duration
4. Add a B to center of the staff
5. On the Note Entry toolbar press "2" to switch to voice 2
6. Add an A to second space from the bottom of the staff
7. Add an F to the bottom space of the staff

Expected behavior: Stems should align to avoid overlapping noteheads between B and A (see "seconds between voices overlapping.png")

Actual behavior: Note heads align when you add the F causing the B and A noteheads to overlap (see "seconds between voices corrected.png")

(Tested using r. 2311 nightly build, Windows XP)