gtk/gtk.go
func (v *Calendar) MarkDay(day uint) {
	C.gtk_calendar_mark_day(v.native(), C.guint(day))
}
func (v *Calendar) MarkDay(day uint) {
	C.gtk_calendar_mark_day(v.native(), C.guint(day))
}
// MarkDay is a wrapper around gtk_calendar_mark_day().