-RM-714-MR-graph: provide user feedback when zooming in
display a rectangle while doing the mouse drag&drop
(from redmine: issue id 714, created on 2011-04-05, closed on 2012-11-27)
display a rectangle while doing the mouse drag&drop
(from redmine: issue id 714, created on 2011-04-05, closed on 2012-11-27)