Rich,
Your question comes at an interesting time if the development life of ScintillaNET. The 2.x version hosted here at CodePlex is no longer being maintained and I'm moving development of the next version to GitHub. The repository is here:
https://github.com/jacobslusser/ScintillaNET
In the project documentation you'll find an example for "custom line numbers" which I've added specifically to answer your question. The principles are applicable to the legacy 2.x version hosted here at CodePlex but I would urge you to also consider upgrading to the new codebase.
Jacob
Your question comes at an interesting time if the development life of ScintillaNET. The 2.x version hosted here at CodePlex is no longer being maintained and I'm moving development of the next version to GitHub. The repository is here:
https://github.com/jacobslusser/ScintillaNET
In the project documentation you'll find an example for "custom line numbers" which I've added specifically to answer your question. The principles are applicable to the legacy 2.x version hosted here at CodePlex but I would urge you to also consider upgrading to the new codebase.
Jacob