Back Button When Viewing Collaborators
Usually when you go "in" or "down" a level by opening a folder or a file within that folder, there is some sort of "go back" feature in Box itself like a file path where you can click back out to the parent folder or an X to close a document. But when you click on the icon to show you who the collaborators on a document are, it seems the only way back is to use the browser's back arrow.
(Also it would be even better to simply show the list of people who can access the file at right the same way it shows up for shared folders. Then you don't have to click into anything.)