Allow resizing of the bookmark sidebar by dragging its border.
Just like the feature requested for codeeditor (#1928).
(from redmine: issue id 1950, created on 2014-10-19 by benjamin.fischer, closed on 2014-11-05)
Just like the feature requested for codeeditor (#1928).
(from redmine: issue id 1950, created on 2014-10-19 by benjamin.fischer, closed on 2014-11-05)