plain-text composer regression?

[barney]

Has anybody else noticed a painting problem with the plain-text mail
composer in nightlies of the past week or so? Like delete a few lines of
wrapped text and half the message in the window disappears? Hiding and
redisplaying the compose window restores it. Seems to me this was a
problem for a while, but was fixed some time ago. It seems to be back.
Or am I the only one experiencing this?