running gnome-terminal --transparent --shaded will eventually result in a crash. Running gnome-terminal using an xterm provides this output:

:~$ gnome-terminal --shaded
Gdk-ERROR **: BadPixmap (invalid Pixmap parameter)
  serial 1592 error_code 4 request_code 56 minor_code 0

This happens after several times of switching in and out of the viewport.  Switching the viewport is about the only way I've seen it crash.  Its intermittent.  I can switch 20 times and not have it crash.  Then I can try again and it will crash within 3 or 4 times. It also exhibits this behavior with just --transparent. (and setting it with the preferences window) After about 35 viewport switches this one crashes with:

Gdk-ERROR **: BadPixmap (invalid Pixmap parameter)
  serial 7829 error_code 4 request_code 56 minor_code 0

I tried to do a backtrace but gdb reports that it exits with a error code of 1.

I posted it on bugzilla.ximian.com as bug 4484 they said to re-post it here.