Well, I don't know if this would be a most wanted feature ... but if I start to write code ... I just click on the "new file" icon, because I am to slughish to click the tiny arrow button next to it, to choose which file or sort of code I plan to write.
Therefore it would be very nice to have a little drop down box in one of the toolbars, where you have the possibility to change the code highlighting of the focused document - even if it is an already stored and reopened file with a specified file extension.
This settings don't have to be saved ... only temporaly for the working session.
Maybe you know the little editor "Weaverslave" (click) - there you have such a feature ... I really liked that, before I switched to RapidPHP.
Greets Evil