builder: allow the tree view to scroll
builder: allow the tree view to scroll

jonnylamb/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx,clutter-project/mx,clutter-project/mx,jonnylamb/mx,pwithnall/mx,pwithnall/mx,jonnylamb/mx