This problem also affects radiotray. There is a workaround, not a real fix. See comment #10 on
this bug report.
At your "/" with root terminal
find . -type f -name SysTray.py
Edit the file SysTray.py, by commenting out line 185. **
** EDIT: After thinking a bit, probably SysTray.py is not the file that is making the gtk call, in the case of gftp. But the same
gtk.gdk.threads_init()
call as SysTray.py makes is probably the cause of your mutex lock error.
"Mutex" is not a real English word, btw -- just a technical term invented for software enginees to describe a "mutual exclusion object" -- see
here.