Double-clicking misplaced tremolo causes unhandled exception

I'm attempting to add a tremolo object to a two note chord.

1) I open the palettes window (F9)
2) I select the bottom note of the chord, so that it is highlighted in blue (1st voice).
3) I double-click on "2 bars through stem" tremolo. This places the tremolo over-top of the second note on the chord.
4) I double-click on the tremolo object, in an attempt to enter "Edit Mode."

Expected result: MuseScore enters edit mode, and I can move the tremolo to a different location on the stem of the chord.

Actual result: MuseScore throws an unhandled exception.

For what it's worth, here's the text of the error message in Visual Studio: Unhandled exception at 0x00434aba in mscore.exe: 0xC0000005: Access violation reading location 0x00000000.

I'm running MuseScore 0.9.3 on Windows XP Home SP3, Intel Pentium 4, 2.40 GHz.

This repro'd three times on my machine.

Help?