Yes, I agree about the weakness of the RTB. Actually I saw a built-in editor control that was very nice in TKInter that comes with Python, because it has marks and tags, which I think I need. A mark represents a floating position somewhere in the contents of a text widget. A tag is like, well, a pair of marks under the one name, which defines a range of characters and those characters can be given a font, a color and other nice properties. Now if I could get that in C# I'd be happy. Maybe I should build my application in Python...