My request is two-fold:
1. Remove the lines that appear between the thumbnail caption lines
2. Left justify the thumbnail labels.
Alternative to #1: give the user control over the color of the lines
Alternative to #2: Let user specify justification of thumb captions
Human factors research has shown that reading "centered" text is much slower than reading "justified" text. Also, the lines between the caption values add visual noise and IMHO make the browser look more cluttered than necessary.
In the image below, the current XnView design is on the right, my proposed design is on the left.

As always, thanks for listening!