Hello, I've managed to make a working lexer for txt2tags. It's based on the markdown one. The patch is in the attachment file. If you accept it, I'll propose it upstream to the scintilla project. On http://geany.org/manual/dev/hacking.html#syntax-highlighting I propose you add something about editing scintilla/include/Scintilla.iface for updating scintilla/include/SciLexer.hBtw, I didn't manage to update the SciLexer.h file from scintilla.iface, so I've manually copied the code in both files.