Say my view is split into A and B. I'd like to be able to pin A such that no matter what happens, no other document will come to foreground in A. All documents should open in B no matter whether my cursor is in A or in B. 

Rationale: one often works with a "master" document and a collection of "satellite" documents. The master document must always remain visible. I think currently there is no way to achieve that - if I forget my cursor in A, and open a new document, it will open in A, and I have to click around to open it in B and go back to master in A instead.