I've recently switched to using the current window for editing src blocks w ~(setq org-src-window-setup 'current=window)~. I like this a lot, and it lets me swtich rapidly back and forth between the parent buffer and source code.  Often when I ma working I split some of hte other windows to display other fn definitions or help buffers. I would strongly perfer for htat window layout not to hcange when I switch back to the parent buffer.  I was able to change this for myself by wrapping the final ~when org-src--saved-temp-window-config~ in the definition of ~org-edit-src-exit~ in an unless statement:

(unless (eq 'current-window org-src-window-setup)
        (when org-src--saved-temp-window-config
          (set-window-configuration org-src--saved-temp-window-config)
          (setq org-src--saved-temp-window-config nil)))

SO far this is working for me but I wondered whether other people would similarly want to change this behaviour and I should put together a proper proposal & patch?