The source code

    Ext.onReady(function(){
        var tree = new Ext.ux.tree.ColumnTree({
            width: 550,
            height: 300,
            rootVisible:false,
            autoScroll:true,
            title: 'Example Tasks',
            renderTo: Ext.getBody(),

            columns:[{
                header:'Task',
                width:330,
                dataIndex:'task'
            },{
                header:'Duration',
                width:100,
                dataIndex:'duration'
            },{
                header:'Assigned To',
                width:100,
                dataIndex:'user'
            }],

            loader: new Ext.tree.TreeLoader({
                dataUrl:'column-data.json',
                uiProviders:{
                    'col': Ext.ux.tree.ColumnNodeUI
                }
            }),

            root: new Ext.tree.AsyncTreeNode({
                text:'Tasks'
            })
        });
    });