Richard Stallman wrote:
>       (GTK crashes when Emacs tries to disconnect from an
>     >>           X server.)
> 
>     The Gtk guys are aware of the problem, see 
>     http://bugzilla.gnome.org/show_bug.cgi?id=85715.
> 
>     The issue is still not fixed as far as I can tell.
> 
> Does the current version work properly with multiple terminals
> when built with GTK?

Multiple X server support is disabled in the GTK build of the multi-tty
branch due to the GTK bug cited above.  On the other hand, multiple tty
device support is fully supported and functional on all builds of
multi-tty, including GTK.  Multiple ttys work, multiple X servers don't.

Incidentally, most of the multiple X display support comes from the
trunk, so the bug is reproducible there as well.  It is unlikely to
occur in normal usage, though: the trunk does not normally disconnect
from an X server, while the multi-tty branch disconnects immediately
when the last frame is deleted. It is the act of disconnection that
triggers the GTK crash.  (Connections must be closed sooner to support
using emacsclient in an SSH session with X forwarding better.)

-- 
Károly