Plugin developers are significantly hamstrung as is since there is no real way to create native sublime UI components. Plugins sometimes have to be shoe-horned in to the limited UI toolset currently available, or do something crazy like launch a local webserver where an adaquate interface can be rendered. If there was an API for better integration with the sublime UI, there would be an opportunity for some much higher quality plugins for things like debuggers, live markdown preview, better integrated color choosers, etc... the list goes on.
I know I have seen this request before somewhere, but I'm not seeing it on the first few pages now, and I think it would be a huge step forward.
Seeing as Sublime is closed source, I can't really tell what other additional functionality/changes this implies, but I'm sure there is some. I may have spent a little time digging through what I could of sublime's available source to see if there was an undocumented way to do anything, but all I found was a useless undocumented API method, a few small errors in the official plugin documentation, and a rudimentary understanding of how the public API delegates calls to the sealed backend .
Does anyone know if Jon has addressed this before?