GtkCalendar::marked_date
Access: Read Only
Type: array
The marked_date property is
an array of 31 comma-separated values, all of which are either the
default false or, if marked, true.
The array count begins at zero, whereas the days in
the calendar begins at 1. You will need to add
1 to an integer representing the position of a
marked date, to compensate for this mismatch.