Trigger NES when switching files

[alexdima]

If I do edits in a fileA, and then immediately switch to fileB, then it would be interesting to invoke NES.
The logic could be:

• if the user did edits in the previous active file
• if the time elapsed since the last edits is under 10 seconds (or some other time)
• if the user didn't land in a diff editor
• then trigger NES, maybe with a large edit window