This is an updated version of Splamy's fork (https://github.com/Splamy/FastColoredTextBox) allowing compiling with Mono
Fast Colored TextBox is text editor component for .NET. Allows you to create custom text editor with syntax highlighting. It works well with small, medium, large and very-very large files.
It has such settings as foreground color, font style, background color which can be adjusted for arbitrarily selected text symbols. One can easily gain access to a text with the use of regular expressions. WordWrap, Find/Replace, Code folding and multilevel Undo/Redo are supported as well.
More details http://www.codeproject.com/Articles/161871/Fast-Colored-TextBox-for-syntax-highlighting
Nuget package https://www.nuget.org/packages/FCTB/