Pull requests and commits have a diff view that shows the files which have changed.

That's great.

Could you please provide an option (e.g. checkbox that can be checked/unchecked) to also show the files which have not changed? (and if they are shown, visually distinguish them from the ones that have changed)

I agree that seeing only the files that have changed is useful to focus on things, but sometimes you need to view them in context, and it is very cumbersome in Stash to be able to look at the source files for the state of the repo branch at that commit.