SSH tunnelled X sessions become unresponsive.

[Andy Burns]

For several years I've used either Cygwin/X or more recently Xming as
an X server for GUI access to Fedora machines from Windows machines,
sometimes with XDMCP but mostly with SSH tunnelling using Putty/Plink.

Recently I tried the same to an F7t2 machine, and again today with a
rawhide machine that must be pretty close to what is going to be F7t3,
Initiating the session with plink.exe and starting gnome-session on
the Fedora box tunnelled back to windows, the Gnome session starts up
OK, the gnome-panel reacts properly to mouse moves/clicks for a few
seconds and then starts running like treacle, only accepting one click
every 60 seconds or so, I've checked the same to an FC6 machine and it
doesn't occur, I've upgraded to the latest Xming version and it
doesn't help.

I *think* the version of Xorg in F7/rawhide now uses XCB underneath
Xlib as the transport, I don't claim to know all of Xorg's internal
plumbing, but could this be related, or be causing some weird SSH/Xorg
interaction?

If I start Xming as a listening X server on the Windows box, then
start a command line Putty/ssh connection to the F7 machine, and
initiate a Gnome session back to the Windows box, with

export DISPLAY=aaa.bbb.ccc.ddd:0.0
gnome-session &

it seems to run for longer, before meeting the same fate

I realise this problem involves Xming (and windows) as well as Fedora,
but it seems to be F7 related, because FC6 and FC3(!) machines still
work OK, any other users doing remote X sessions and having problems?