Update -- The query and admin functionality all seem fine. It's just the modelling portion that tanks.
Not sure what happened but the data modeling portion (maybe more - haven't checked) of MySQL workbench is completely unusable on my Fedora 18 machine. I've tried everything I can think of and Google doesn't turn up anything - so I don't know what the cause is, but I can't use it. Which is too bad. I like the tool a lot. I get it up and going but pretty quickly it becomes slow to the point of appearing unresponsive. Later when I feel like messing with it more I'll try to dig around and see if I can figure it out. I don't have to use it - I can just write out everything but sometimes visual tools like that help me process - and I could draw it on paper but it's nice to make my picture and then just get my sql with it automagically.
And while I'm here - in somewhat related news - I reported earlier that swing fonts were looking better on my system and I wasn't sure why. I can now confirm that if I don't use OpenGL as my compositing type they don't look so good. The java options for font rendering seem to have no impact but if I switch compositing to XRender the font appearance become crappy. This is with the NVidia driver. So that feels a little bit like less of a mystery.