Cups stuck in landscape? Try gtklp

My printer (Lexmark Optra 312L, hanging off a Gentoo box's parallel port) had been stuck in landscape mode for a while. I couldn't find anyplace in the cups web GUI to fix this. Someone on the Gentoo forums recommend backing up then nuking /etc/cups, uninstalling then reinstalling cups, and reconfiguring the printer. That didn't work either.

Then I found gtklp. It's a little gtk app with the Tabbed Dialog From Hell interface. One of the 9 tabs is labeled Output. The Output tab has a portrait / landscape selector. Switched to portrait, hit save, and now the printer is back in portrait mode.