After upgrading to 12.1, I've noticed a very annoying and persistent bug with regard to keyboard input. Whenever I summon a dialog box (for instance with Control + F for Find, or Control + E for "tag selected text"), if I start typing a little too quickly, before the dialog box is fully instantiated, the keyboard ceases to work. Whatever I do after that, I can't type anything into that dialog box again; I have to dismiss it with the mouse and start again. It's especially annoying because it afflicts me when I'm working really efficiently and quickly.
Has anyone else seen this? I'm using Ubuntu Lucid 64-bit, and I see the same problem whether I use the JRE that ships with oXygen or the up-to-date JRE from the Ubuntu repos.