PhotoStructure tries to choose a sensible amount of thumbnails to be shown at the same time, depending on the screen size. Users might prefer to see more or less thumbnails.
Suggestion by @mrm: “I was thinking about adding a “+” and “-” button in the headers to show more or less rows of thumbs… would that work?”
This will also help people with libraries that span tons of years, or have tons of keywords. Currently it’s a lot of scrolling to get through tags with tons of children.
I guess this should be stored as a user preference, like thumbnail size?
The next release will contain both a dropdown in the tag header that lists all direct child tags, as well as a +/- in the tag header to control how many rows of thumbnails to display.