Created attachment 4607
screenshot of the issue
When I logged on today, I noticed my windows had been censored: where all the titles should have been, a piece was cut out of the window decoration. Messing around with things, I found out that changing the "title-3-active.xpm" and "title-3-inactive.xpm" pieces in the theme I was using (cruxish, from xfwm4-themes on my distro) from 1 pixel wide to 2 fixed this. Furthermore, the several pieces of several themes that I changed to 1 pixel wide failed to show up.
The only packages I updated before this happened seem unrelated to me:
gc (7.2-1 -> 7.2.c-1)
hspell (1.1-2 -> 1.2-1)
hwids (20120730-1 -> 20120815-1)
initscripts (2012.08.2-1 -> 2012.08.3-1)
libatasmart (0.18-2 -> 0.19-1)
libgssglue (0.3-1 -> 0.4-1)
udisks (1.0.4-4 -> 1.0.4-5)
winetricks (20120308-1 -> 20120819-1)
wireless_tools (29-6 -> 29-7)
xorg-server-common (126.96.36.1991-1 -> 1.12.4-1)
xorg-server (188.8.131.521-1 -> 1.12.4-1)
Doesn't look like an issue in xfwm4, could be a possible regression in the Xorg stack.
The portion of code in xfwm4 hasn't been touched for years, I don't see why it would fail at now, without anything being changed.
Does it make any difference if you downgrade xorg-server-common and xorg-server?
Downgrading xorg-server and xorg-commong fixed this, so it looks like that's the problem package.