There are a lot of problem:
if from console you start the program with the option -XstartOnFirstThread, you can't do anything when the program start (click or do other thing), without the program start. After it connect to a Server the button Connect doesn't change in Disconnect
and if I re-click it obviously say "JMule is already connected (connecting) to another server".
Now the program start, but inside the program is impossible to select a different UI, when I click on UI Chooser the program stops responding and I have to kill it from shell. When I start the program, even if I don't do nothing (I don't connect to any server) after a few minutes the CPU goes to 100%
(I don't know why, but I think is a problem of SWT).