It would be useful a file drop feature for tuxguitar. That is, give a window of tuxguitar open, the user could drag&drop a file from explorer (or nautilus or whatever) onto this window and tuxguitar opens the file that the user just dropped.
This would prevent opening multiple istances of tuxguitar for different files or using tuxguitar's file->open and search for the file if you have it ready in explorer.
This should not be too difficult to implement. Given that the open feature is alredy here, it's only about incercepting a drag&drop event.
(Disclaimer: I am not a TuxGuitar dev)
This is already implemented on OS X; I guess something similar could be done on Linux and Window. I think TuxGuitar has a limitation that it can't open more than one document at a time, so some people could be annoyed that opening another file closes the current one