On a hand-built installation of gnome, gnome-about refused to open any links (http://www.gnome.org and others) when I clicked on them. Traced it down to gtk_show_uri() failing with "Operation not supported". Googling around, it's almost a FAQ that that happens when you don't have gvfs installed. And that even on vendor distros, it's sometimes not possible to have dependencies that make sure it's present. The devhelp for this function just says that it uses gio, with no specific pointers to help me here. So...how about an explicit note in the doc for gtk_show_uri() saying that it requires gvfs in order to handle many uri types? It's an implementation detail for gio, but it's a user-visible broken behavior here and hard to get from here to any explanation about how to fix it.