Set the "Viewed" flag in a MR diff by clicking on the file

I understand that in the default MR diff view (no file browser and “Show one file at a time” disabled) it is hard to automatically determine whether the user has viewed the changes in a certain file. However, if a user has the file browser pane on the left enabled, and has selected “Show one file at a time”, it seems intuitive to me that, when the user has clicked on a file in the browser, he has consciously looked at its changes and therefore the file may be marked as “Viewed”. To me, and many of my collegues, it is cumbersome by clicking the Viewed checkbox for every file. Is there an option somewhere I have missed that enables this behaviour?