I just ran spark on Ubuntu x86_64, when opening preferences, it opened to ~ 10x8 pixels, but could be resized…
this seemed to happen on a couple of other popups too. And keyboard entry seems to not work for all but the Chat text entry (properties, profile editing, add buddy), the cursor may be flashing but there are no keystrokes being recorded.
I replaced the packaged JRE with SUN 1.5.0_11 adn the editing / Preference issues dissapeared…