Good idea this!
A related suggestion: some way to temporarily make it harder to close the FARR window. (like the "protect tab" feature in Firefox).
I have enabled "Close Window after launch by default" and very often close FARR with esc. With the Html View Mode I at least have started to use FARR in slightly new ways (and I suspect that I won't be the only one doing so). Previously, I never had it visible more than a few seconds - open, find, run, close. Now I've also started to use it to display html files, websites or things like that that I want visible slightly longer while doing things in another window. But then it is very easy to accidentally close FARR. So a protection option makes sense.
more brainstorming on this idea:
Some visual indicator when FARR is in a protected state would be good also.
ctrl + escape could enable protection
double-tapping escape (or clicking the upper right corner X) could break the protection and close FARR