Crash when changing pattern size during playback

[freq-mod]

I know it's obvious why this crash happens, but anyway:

1. Create an instrument
2. Lay a note
3. Play a "song"
4. Now, double click on "pattern size" and change default value (64) to something like single-digit.
   It may not work on the 1st try, but on 2nd, 3rd or so it's guaranteed to crash to desktop.
   Proof:
   

[rerrahkr]

Thanks for your report, I fixed it at 6ba887e. In this commit, I also changed spinbox behavior to emit value change event when finishing text editing.

[freq-mod]

Thanks for the fix!