    /**
     * @class Ext.grid.RowNumberer
     * @extends Ext.grid.column.Column
     * This is a utility class that can be passed into a {@link Ext.grid.column.Column} as a column config that provides
     * an automatic row numbering column.
     * <br>Usage:<br><pre><code>
    columns: [
        Ext.create('Ext.grid.RowNumberer'),
        {text: "Company", flex: 1, sortable: true, dataIndex: 'company'},
        {text: "Price", width: 120, sortable: true, renderer: Ext.util.Format.usMoney, dataIndex: 'price'},
        {text: "Change", width: 120, sortable: true, dataIndex: 'change'},
        {text: "% Change", width: 120, sortable: true, dataIndex: 'pctChange'},
        {text: "Last Updated", width: 120, sortable: true, renderer: Ext.util.Format.dateRenderer('m/d/Y'), dataIndex: 'lastChange'}
    ]
     *</code></pre>
     * @constructor
     * @param {Object} config The configuration options
     */
    Ext.define('Ext.grid.RowNumberer', {
        extend: 'Ext.grid.column.Column',
        alias: 'widget.rownumberer',
        /**
         * @cfg {String} text Any valid text or HTML fragment to display in the header cell for the row
         * number column (defaults to '&#160').
         */
        text: "&#160",

        /**
         * @cfg {Number} width The default width in pixels of the row number column (defaults to 23).
         */
        width: 23,

        /**
         * @cfg {Boolean} sortable True if the row number column is sortable (defaults to false).
         * @hide
         */
        sortable: false,

        align: 'right',

        constructor : function(config){
            this.callParent(arguments);
            if (this.rowspan) {
                this.renderer = Ext.Function.bind(this.renderer, this);
            }
        },

        // private
        fixed: true,
        hideable: false,
        menuDisabled: true,
        dataIndex: '',
        cls: Ext.baseCSSPrefix + 'row-numberer',
        rowspan: undefined,

        // private
        renderer: function(value, metaData, record, rowIdx, colIdx, store) {
            if (this.rowspan){
                metaData.cellAttr = 'rowspan="'+this.rowspan+'"';
            }

            metaData.tdCls = Ext.baseCSSPrefix + 'grid-cell-special';
            return store.indexOfTotal(record) + 1;
        }
    });