[BZ#441608] keep directories folded after reload
Submitted by Antti Kaihola
Assigned to Stephen Kennedy
The folding state should be remembered and restored after a refresh.
Other information: All directories are currently unfolded after refreshing (at least in svn mode). I frequently fold most of the tree, and it's annoying to have to fold them again after each commit (meld auto-refreshes after svn commit).