Might want to check-out the KiXscripts Editor. A language sensitive (syntax high-lighting) editor engineered specifically for KiXtart scripting. Even has templates (dialogs) for setting-up calls to common functions. Another neat feature is the EXE packager that can take your scripts and package them into EXE's.

Fairly-priced at $39 USD last time I checked.

No, I dont work for Kixscripts but a few of the regulars around here use it. And like it from what I understand.