How do I trap for Select All in a dxDataGrid, using Typescript

Question

I have a dev express datagrid, with header filters. If I select single or multiple entries from the filter, this is picked up by the calculateCellValue and calculateFilterExpression for that column:

    columns: [ ...

    {
                    dataField: 'communityName', caption: 'Community', alignment: 'center',
                    calculateCellValue: calculateCellValue,
                    calculateFilterExpression: (filterValue, selectedFilterOperation) => {
                        // pick up the filterValue & repopulate the map markers
                        this.$scope.community = [];
                        this.$scope.community.push(filterValue);
                        console.log('filterValue: ' + filterValue)
                        this.createMapMarkers(); 
                        return [calculateCellValue, selectedFilterOperation || '=', filterValue];
                    },
                },

However, when Select All is chosen, this event is not triggered.

How do I trap for this please?