This is breathtakingly minor. But it does affect my workflow, so here goes:
I shoot a lot of catalogs. I rename images to reflect a shot's content, using a hierarchy of descriptors while retaining an ongoing sequence, i.e., "waffles-butter-melt_{seqn}" and "waffles-syrup-pour_{seqn}".
When renaming batches, there is a lot of single-word replacement. Double-click a word for replacement and adjacent dashes are not selected. This is good.
Problem: adjacent underscores are selected. When renaming thousands of images, the time spent carefully dragging around the underscore really adds up.
In short, I'd prefer that the text engine regards underscores the way it regards dashes.
(Do I win an award for the most precious quibble ever?)