/* Sets the calendar widgets to the date range of the model */
    void sync_with_model () {
        var model = Model.CalendarModel.get_default ();
        if (grid.grid_range != null && (model.data_range.equals (grid.grid_range) || grid.grid_range.first.compare (model.data_range.first) == 0))
            return; // nothing to do

        DateTime previous_first = null;
        if (grid.grid_range != null)
            previous_first = grid.grid_range.first;
        var previous_big_grid = big_grid;
        big_grid = create_big_grid ();
        stack.add (big_grid);

        header.update_columns (model.week_starts_on);
        weeks.update (model.data_range.first, model.num_weeks);
        grid.set_range (model.data_range, model.month_start);

        // keep focus date on the same day of the month
        if (selected_date != null) {
            var bumpdate = model.month_start.add_days (selected_date.get_day_of_month() - 1);
            grid.focus_date (bumpdate);
        }

        if (previous_first != null) {
            if (previous_first.compare (grid.grid_range.first) == -1) {
                stack.transition_type = Gtk.StackTransitionType.SLIDE_UP;
            } else {
                stack.transition_type = Gtk.StackTransitionType.SLIDE_DOWN;
            }
        }

        stack.set_visible_child (big_grid);
        //Timeout.add (stack.transition_duration, () => {
            previous_big_grid.destroy ();
          //  return false;
        //});
    }