Highlight the current thumbnail in a collection

Please look at the attached image and answer this question: which thumbnail am I looking at?

If I open a collection and then double click to look closer at one of the images, there is no indication on the thumbnails of which image I’m looking at. When working through many iterations it becomes very difficult and frustrating to keep track of them all.

Would be great if you could add a purple border around the thumbnail that is currently in the edit window.