SMART datagrid v.1 > Classes > TextCellEditor
The maximum text length which can be edited. 
If specify as less than 0, you can enter without limit.
Defaults to 0.
    var columns = [{
        name: "col1",
        fieldName: "Data1",
        editor: {
            maxLength: 20
        },
        ....
    }];
    grid.setColumns(columns);
    column && column.setEditor({
        maxLength: 20
    });