SMART datagrid v.1 > Classes > GridBase
Index within data set of grid row which currently has input focus. 
You can know grid row index through focusedRowIndex and cell location through focusedIndex.
    $('#delete').click(function () {
        var row = grid.focusedDataIndex();
        if (row >= 0) {
            dataset.deleteRow(row);
        }
    });