Wow the upgrade to Thunderbird 9.1 rendered my display font fuzzy, jagged, and intensely difficult to read. This is true of the menus, tools, inbox headlines, and the messages themselves. I've tried all the tricks to change my display font but it isn't changing. What else can I try? (I'd post a screenie but, weirdly enough, the font looks fine in the screenshots! Also, I am not having this problem in any program except Thunderbird, and everything was fine there, too, yesterday before the upgrade hit me.)