Is there an overlay that warns the user if the frame is not completely filled?

Hey there, 

since we have to work with different aspect rations and projects from different people it happens from time to time that one clip is not properly allignt and therefore a little black border is visible in the final render. I wondered if there is an overlay for that, which you can turn on that shows you in the programm monitor if some space is empty? Instead of a small barely noticeable black border some more visible orange or red diagonal lines? This would be very handy but so far I couldn't find such a function. Maybe I just didn't find it because I searched for the wrong name? 

I am curious about your feedback 🙂