Q: howto find xorg leak?

[D. R. Evans]

This is slowly wearing me down, and I'd love to find a way to solve it:

Running amd64 dapper, with KDE 3.5.5, xorg grows at the rate of about
300 to 400 MB of memory per day. After googling around, I discover
that almost certainly this is not actually a leak in xorg, but in some
program that is using xorg. But how do I discover which program? I
have been through the system, killing all the obvious candidates
(basically, the application programs that put stuff on the display),
but the memory never seems to decrease; the only way to "fix" the
problem is to log out and restart the X server.

It gets pretty tedious having to watch one's memory usage all the time
(I have programs that use > 1GB, and if I run a couple of those, and
xorg has been in use for a few days, even my 4GB box gets maxed out),
and having to reboot at least once a week just because memory is
leaking in bucketfuls on to the floor.

So, can anyone suggest a way to figure out which program is causing the leak?