Hello fellow scripters!
I've been using the ArmA 2 Syntax Highlighting that Nicolas made back in 2009 . I've noticed that he hasn't updated it in a long time and that nobody else seems to want to take a crack at updating it, so I thought I would.
It's missing some commands that were added in the OA era, but it has all ArmA 2 and all known ArmA 3 commands now.
Please feel free to modify/contribute and I'll update this post.
Credits
Install Instructions
Notepad++ Language XML