Quoting Troels Henriksen (athas@sigkill.dk):
This patch by David Lichteblau (http://common-lisp.net/pipermail/mcclim-cvs/2006-November/000612.html) causes problems in McCLIM with respect to redisplay - sheets are not fully redisplayed, but are cutoff some pixels from the edge, at least with the CLX backend. I don't know enough about how sheets work in McCLIM to feel comfortable fixing this, but I hope this message will catch the eye of some McCLIM hacker who can figure out the right fix.
Okay -- looking at your screenshot (thanks!) that seems just like the similar problem I have with Gtkairo. So although Gtkairo has much more trouble of this sort, it probably indicates that the underlying problem is not in the backend after all.
I will either fix or revert this (unless someone else does it first).
David