Hi Stef,

> (MCWorkingCopy forPackage: (MCPackage new name: 'OmniBrowser')) unload.
> (MCWorkingCopy forPackage: (MCPackage new name: 'OB-Standard')) unload.
> SystemBrowser removeObsolete
> 
> and I get the OmniBrowser classes removed bu not the OB-Standard ones

I once had the same problem because OBCodeBrowser was registered in 
SystemChangeNotifier events, so it couldn't get unloaded. But I got a debugger in 
that case, probably it's something else in your case then.
Anyway, I then executed 'SystemChangeNotifier uniqueInstance releaseAll'. Afterwards 
I could unload OB-Standard without problems (was also in 3.9).

David