I guess you can kind of mod Ableton Live using Max4Live, although while you can add new tools and connect to existing tools, you can't (last time I played with

I guess you can kind of mod Ableton Live using Max4Live, although while you can add new tools and connect to existing tools, you can't (last time I played with M4L a few years ago) change any of the core widgets, so its definitely not as deep as what I understand you to be saying.