Since the calendar row widget is becoming an expandable widget, several APIs were added to the widget: - `gcal_calendar_row_get_calendar` - `gcal_calendar_row_add_suffix` - `gcal_calendar_row_get_first_suffix_child` - `gcal_calendar_row_add_header_class` - `gcal_calendar_row_remove_header_class` Part-of: <https://gitlab.gnome.org/GNOME/gnome-calendar/-/merge_requests/362>