Walden Thank you for your kind words about Tonfotos!
Walden Is there any way to determine the -count- of photos that Tonfotos has indexed? Not just in a single folder, but in total?
Yes, in the “Library locations” dialog when you select location you will see its stats, including files count. However, it will not be there until initial indexing is done, so you should wait.

Walden On the tool’s “Location” tab a very small number of my photos appear as thumbnails on the world map. I assume that Tonfotos is deriving these locations from GPS in EXIF data. However, if I click on any thumbnail to view/enlarge, I get a “No results found” error. Is this a bug or is there a workaround/hack to enable these thumbs to be viewed?
When you select location it gets added as another filter, it does not replace all other filters you already added before. So if there are other filters added (like by folder, or by person) that could end up that no files match all those filters at the same time.