Hmm... Too much whining on this blog recently. So let's demonstrate some small, but exiting code I've wrote for Openismus, and which will show up in GTK+ 2.16:
* @calendar: a #GtkCalendar.
* @func: a function providing details for each day.
* @data: data to pass to @func invokations.
* @destroy: a function for releasing @data.
* Installs a function which provides Pango markup with detail information
* for each day. Examples for such details are holidays or appointments.
* That information is shown below each day when #GtkCalendar:show-details
* is set. A tooltip containing with full detail information is provided,
* if the entire text should not fit into the details area, or if
* #GtkCalendar:show-details is not set.
* The size of the details area can be restricted by setting the
* #GtkCalendar:detail-width-chars and #GtkCalendar:detail-height-rows
* Since: 2.16