I'm interested in discussion and addition of features that are relevant to the ways in which Arduino is different than Processing. There are lots of these: the fact that we're uploading to external hardware, that there are circuits involved, that there's a serial monitor, etc, etc.
But besides adding shiny (new?) features to the ide that gets buggy again on the next release, thanks to synchronisation, there is more to be done. There are users, including me, who would rather put their hands into a deep frier than using the ide for all to obvious bugs which never get in any way fixed. Take for example the bug that once you open a document you have two windows. Such things should be maintained by our dev team, no matter what.
In the particular details of text editing and window management (as shared by Processing), you're right that I'd rather defer to Processing.
Thats the whole point. As of nearing 1.0 you should consider giving up that mentality and finally take some responsibility. What do you think will we gain from processing anyway? As you said above all the vital parts are already your work anyway. So why not making the final cut and have our own IDE?