Please allow me to make a suggestion on the rename pop-up whilst viewing images.
Currently: 1. pop up can not be resized, 2. the "New Name" has no additional 'options/modifiers' same as with a 'normal' rename.
Positively meant suggestion: add a Rename button to the bottom toolbar (same as F2) that will bring up a rename panel with the same Old name/New name boxes as with the usual Rename.
This will add the additional options of the regular Rename and solve the resize matter.
It would roughly be like this.
Again, just a suggestion.