Bug with grid snap enabled note length increase

I've encountered this in the past before, but under certain unknown conditions, 
attempting to increase a note's length beyond a beat marker/anchor will result 
in the note length being reverted back to its existing length.  A chart that 
can reproduce this issue is here:
http://www.sendspace.com/file/a7uhc4

By opening this chart, selecting the Pro Guitar track's medium difficulty and 
selecting the last note (#594, at position 83187), any attempt to increase the 
note length with the scroll wheel or the ] key result in the chart being marked 
as modified but the note length does not change.  Through trace debugging, I 
have determined that in eof_adjust_note_length(), the note length is being 
adjusted, but the call to eof_note_set_tail_pos() is reverting the adjustment 
having the net effect of canceling the lengthen operation.

The bug can be worked around by disabling grid snap, increasing the length 
beyond the beat marker and re-enabling grid snap.

Original issue reported on code.google.com by raynebc on 30 Jan 2011 at 8:08

m0j0hn / editor-on-fire

Bug with grid snap enabled note length increase #232