First thing it does is download manpages from developer.apple.com. This takes awhile. It also populates a pane on the left side of the dialog with downloadable-from-apple manpage titles. It seems reasonable to ask whether this pup knows about /usr/local manpages, or offbeat non-standard stuff "man psql" if you happen to have PostgreSQL installed. It's hard to determine, because as I write this, the manpage download from developer.apple.com seems to have stalled. As a workaround, you could try xman (if you have Darwin installed), or just do "man whatever | aless" from Terminal, if you have a copy of aless in your /usr/bin directory (it's not in the Man viewer titles pane, I can tell that much). Loading Man pages is still stalled, so... good luck!