The source code

    Ext.ns('Ext.ux.grid');

    /**
     * @class Ext.ux.grid.CheckColumn
     * @extends Object
     * GridPanel plugin to add a column with check boxes to a grid.
     * Example usage:
     *
    // create the column
    var checkColumn = new Ext.grid.CheckColumn({
       header: 'Indoor?',
       dataIndex: 'indoor',
       id: 'check',
       width: 55
    });

    // add the column to the column model
    var cm = new Ext.grid.ColumnModel([{
           header: 'Foo',
           ...
        },
        checkColumn
    ]);

    // create the grid
    var grid = new Ext.grid.EditorGridPanel({
        ...
        cm: cm,
        plugins: [checkColumn], // include plugin
        ...
    });
     *
     * In addition to storing a Boolean value within the record data, this
     * class toggles a css class between 'x-grid3-check-col' and
     * 'x-grid3-check-col-on' to alter the background image used for
     * a column.
     */
    Ext.ux.grid.CheckColumn = function(config){
        Ext.apply(this, config);
        if(!this.id){
            this.id = Ext.id();
        }
        this.renderer = this.renderer.createDelegate(this);
    };

    Ext.ux.grid.CheckColumn.prototype ={
        init : function(grid){
            this.grid = grid;
            this.grid.on('render', function(){
                var view = this.grid.getView();
                view.mainBody.on('mousedown', this.onMouseDown, this);
            }, this);
        },

        onMouseDown : function(e, t){
            if(t.className && t.className.indexOf('x-grid3-cc-'+this.id) != -1){
                e.stopEvent();
                var index = this.grid.getView().findRowIndex(t);
                var record = this.grid.store.getAt(index);
                record.set(this.dataIndex, !record.data[this.dataIndex]);
            }
        },

        renderer : function(v, p, record){
            p.css += ' x-grid3-check-col-td';
            return ' ';
        }
    };

    // register ptype
    Ext.preg('checkcolumn', Ext.ux.grid.CheckColumn);

    // backwards compat
    Ext.grid.CheckColumn = Ext.ux.grid.CheckColumn;