For some reason today, I can no longer see the windows associated with Classic apps. The apps launch, and I can manipulate them using keyboard commands, but I can't actually see what I'm doing. I also noticed some pieces of Carbon app windows not completely disappearing upon quit. My guess is that there is something wrong with Aqua, but I'm not that knowledgable of X.
BTW, I've been using X (10-10.1) since March and this has never happened before. A restart doesn't fix the problem.