I haven't been working very much with AHK in the last months, so I haven't looked further for a good solution.
I remember discussion on the SourceForge forum of NP++ about the lexer with you and love how great it is now
I have downloaded it a few minutes ago and I really like it. Now I'll try to get it working nicely with a dark layout. Thank you so much.
EDIT: Ok, looks great now. I've got a question: Is it supposed that the highlighting of a variable looks like
[color=brown]MsgBox %[/color][color=cyan]variable[/color][color=brown]%[/color]and not like
[color=brown]MsgBox[/color] [color=cyan] %variable%[/color]
EDIT 2: I think It's the same as questioned before in the thread
I hope this will be achieved some day
I would recommend including  as a SYNOPERATOR. Also, it would be nice if % wasn't grouped with the other SYNOPERATORs. IMO, it would be nice to have this colored the same as the variables, but different than the other SYNOPERATORS - like autoit variables. Plus, it would be nice if a single % was highlighted for forced expressions.
I think the most of AHK_L syntax changes could be implemented in the AHKExternalLexer.xml in plugins\Config\AHKExternalLexer.xml folder. Adding things like Until and #If should work there, too, but I haven't tried it yet. I'm also moving to AHK_L, so maybe I will change the xml by myself when I'm working on a larger project again
Since, this is going to be rewritten, could you add syntax highlighting for AutoHotkey_L? (#If, Until, etc)
I'm sure you saw the announcement that Chris is moving on, and since AutoHotkey_L is going to be the maintained version now, it seems like the syntax highlighting should support all of the new commands/directives.