> Should I report such a bug on Mantis? I know there are changes in the
> core of OB so maybe it's a temporary bug which came from some short
> hacks.

Yes, this is a bug. The latest OB is independent of any GUI and uses a
special package to do the UI. I ported this package to 3.9 so that it
produces a useable GUI. I didn't change much from the orignal code, so
it would be the best to try the latest OB in Squeak 3.7 and 3.8 to see
if it breaks there as well when the scroll bars are on the left.

Cheers,
Lukas

-- 
Lukas Renggli
http://www.lukas-renggli.ch