Louis
My apologies, it would seem that you are correct about the wavy lines not being removed. I have created a small sample which I believe does what you originally wanted to do anyway (give the users a choice as to whether they spell check a document or not). It’s vb as opposed to C# but I don’t think you’ll have any problems figuring out what is what.
I think that the fact that the wavy lines are not removed when one toggles the check as you type facility of the spell checker could be construed as a bug, having said that I suspect that in reality one really needs to redraw the editor and that may be more difficult.
Dom