I played with this a bit tonight. It looks good!
- - debug message about "References2D"
- aspect ratio of symbol when text gets longer. Should it turn into rectangle when text length >> text height?
- point of the leader slides past ends of edge. Would be nice if it stopped at the ends, but not a big deal for v1
- label could be just "Reference". the tree is very crowded aready.
- not sure this is a "dimension". "reference" and "balloon" should go into annotations menu some day. maybe a separate gdt menu.
- next sequential reference - see DrawPage.NextBalloonIndex()