Gets whether the user can sort the data provider items by clicking on a column header cell.
If true, the user can sort the data provider items by clicking on a column header cell. The DataGridColumn.dataField property of the column or the DataGridColumn.sortCompareFunction property of the column is used as the sort field. If a column is clicked more than once the sort alternates between ascending and descending order. If true, individual columns can be made to not respond to a click on a header by setting the column's sortable property to false.
When a user releases the mouse button over a header cell, the DataGrid control dispatches a headerRelease event if both this property and the column's sortable property are true. If no handler calls the preventDefault() method on the event, the DataGrid sorts using that column's DataGridColumn.dataField or DataGridColumn.sortCompareFunction properties.
The default value is true.