Shift-X with measure selected -> crash

1.1 prerelease 2 (build 4535)

1. create score, enter some notes
2. select a measure
3. shift-X

Result: crash

Expected result: all note heads in measure flip to opposite side of stem.

OK, not something one might normally do, so I don't know that this is *really* critical. I ran across it only because I was hoping shift-X might reset a stem flipped via "X" to the default. After getting a crash, I looked it up and realized what shift-X really does.