external interface for selection (to be IDL-ified later). Fix some editor bugs: - Advance the cursor on text insert (so text is inserted in the right order) - Make DeleteSelection in the editor call the actual selection - Make DeleteSelection update the frames' notion of the selection git-svn-id: svn://10.0.0.236/trunk@19029 18797224-902f-48f8-a5cc-f745e15eee43