Rich Text Box Line Counting

Question

I'm looking for resources on how to develop something similiar to SharpDevelop's RTB. If you view this screenshot: http://sharpdevelop.sourceforge.net/tourimages/094/ccdb_ccinaction.png You will see the numbers are seperated on the left, I was wondering how this can be reproduced for Microsoft's default Rich Text Box, with C# 2.0. Also, I was wondering what is the best method to do syntax highlighting. Phrase the text with regex? Thanks!