Background: While reviewing suggested edits, I often scroll down to the very bottom to see what all changes were there. Most of the times it's just code formatting (on Stack Overflow) so after having had a look at everything till the bottom, I just click Approve. But sometimes, the edit reason is not immediately obvious. In this case, I have to scroll all the way to the top to see the edit reason, then go till the bottom to see if the edit tallied with the reason.
Hence, as shown in the above image, I wish the empty space next to the left of the buttons can be used for this work. That way, even if I scroll to the bottom, the edit reason stays there in front of me, like this: