Introducing: JanaGtkMonthView
It's not quite there yet (and the code isn't committed), but I've almost finished (sort of) one of libjana-gtk's major widgets - the GtkCalendar style event view. It uses the previously demonstrated JanaGtkTreeLayout to deal with drawing/updating/activating events and draws the background/handles positioning itself. It doesn't handle selections or anything like that yet (although of course, JanaGtkTreeLayout still works, so you can select events). It's also fully themeable, so a theme can choose to special-case it and give it more appropriate colours/look, for example.
[Update]: Committed