Mike Kupfer Wed, 09 Dec 2015 20:03:54 -0800
With synaptic 0.82.4 libgtk-3-0 3.18.6-1
the scrollbar now appears when it's supposed to. So I guess this bug can be closed. (I can confirm that the problem was still present with libgtk-3-0 3.18.5-1.) mike
