don't be stupid about finding the insertion point onto the tree for new rows. use GetInsertionPoint to walk the frames to determine the appropriate row index for new content that doesn't already have frames, so that the rows in the cellmap get the right index.
r=hyatt, bryner@uiuc.edu, alecf (some code dictated by hyatt)
git-svn-id: svn://10.0.0.236/trunk@53324 18797224-902f-48f8-a5cc-f745e15eee43
7f77950d2c