Hello,
The Show Class button opens a browser window explaining a selected class, for instance type short, hit <enter>, and afterward click Show Class:
http://java.sun.com/j2se/1.4.2/docs/api/…ort.html#%28%29 opens.
I don't think there is a need to click that button without choosing a class

, but this is a GUI-related bug, that should be solved by ignoring the click when nothing is selected.
BTW (Manuel): Any progress with the images issue? Eagerly waiting for the next version..
Regards,
Amit