updateSummaryGrid: function(data) {
        var ds=this.detailGrid.getStore();
        var day0 = ds.sum('day0');
        var day1 = ds.sum('day1');
        var day2 = ds.sum('day2');
        var day3 = ds.sum('day3');
        var day4 = ds.sum('day4');
        var day5 = ds.sum('day5');
        var day6 = ds.sum('day6');

        // update master based on the _current_ selection
        // potential race condition here... but not very likely.
        var selections = this.masterGrid.getSelectionModel().getSelections();
        if ( selections.length === 1 ) {
            var d = selections[0].data;
            var ms = this.masterGrid.getStore();
            ms.suspendEvents(false);
            if  ( day0 && day0 !== d.day0  ) d.day0 = day0;
            if  ( day1 && day1 !== d.day1  ) d.day1 = day1;
            if  ( day2 && day2 !== d.day2  ) d.day2 = day2;
            if  ( day3 && day3 !== d.day3  ) d.day3 = day3;
            if  ( day4 && day4 !== d.day4  ) d.day4 = day4;
            if  ( day5 && day5 !== d.day5  ) d.day5 = day5;
            if  ( day6 && day6 !== d.day6  ) d.day6 = day6;
            ms.resumeEvents();
            this.masterGrid.getView().refresh();
        }
    },