When I use Preview in side-by-side mode, the title bar may show something like this:
Preview for GVC080108x0331.nef+jpeg (4256 x 2832 14679K+3071K) 15% and GVC080108x0369.nef+jpeg (4256 x 2832 15857K+3073K) 15%Can you imagine that it's a bit hard to find out that you are comparing picture 331 with picture 369 in this case? I often find myself pointing with a finger on the screen to keep track of the file numbers...
Would it be a good idea to clean this up a little bit?