"(and without closing the Find bar)" - which is not the case yet. closeBlur is set to close the bar in ModalBar right now. I totally agree to leave highlighting while dialog is open (as Chrome and Intellij works), but right now it closes on blur, so ... 

"what to do if edits create/destroy matching text while highlighting is on. "
I see your point. Intellij updates highlighting on every edit.

"NJ's changes"  - what is this?

Your last comment about detaching the editor etc is more general problem for search functionality, not related only to highlighting part?

I like the idea of continues delivery, where all this will be done incrementally.