I am using SVN 3875 (24/09/2010).
Spec: Linux, Sun Java 1.6.0_20-b02 64bit, 8 GByte RAM, Core2Quad 2,66 GHz (Q9450)
The seven feature buttons in the top left corner have a behaviour that I consider buggy:
1) They are the most important buttons of the whole program (in fact the only buttons?), but they hide all the time instead of offering themselves to be used.
2) They do not have names and/or tooltips. It is hard to find documentation or write a bug report without knowing what the strange symbol stands for.
3) Even when not considering the hiding, it is very hard to use the mouse to switch a feature. It would be very helpful to have some dedicated hotkey for each feature.
4) Sometimes, I can't figure out the details here, the buttons hide but do not come back. I am using a dual monitor setup using NVIDIA TwinView and xmonad (which is xinerama aware). zgrviewer currently runs on the right screen in full size.