When I close OpenSong either by clicking on the top-right X or by pressing Alt-F4, I get a segfault. If I close from the File->Exit, it doesn't crash.
The core file is 158MB, so I won't send that unless you want it.
I have attached two log files from running "strace opensong", one when it crashed and one when it didn't. Hopefully that'll help you figure it out.
3.4.8 on debian linux, using the released .deb from sourceforge.
Anonymous