Patch Set 6:

I'm almost done with "OK" button. Issue mentioned by Remy is now fixed, but one that Matthias picked up is still existing. I'll work on it tomorrow and I think that until tomorrow evening I'll send new patch set.

Right now I'm not quite sure what done with ExpandableComposite and Expansion(Event/Adapter), I don't want to implement on my own, and copying them inside EGit is also not an option. Maybe someone has some ideas or suggestions in this case ?