（分页工具栏）上需要显示（GridPanel显示的数字列的和）怎么做？
目前我已经得到了（GridPanel显示的数字列的和）但是显示不到分页工具栏上

Ext.onReady(function(){
var store = new Ext.data.JsonStore({
root: 'topics',
totalProperty: 'totalCount',
idProperty: 'threadid',
remoteSort: true,
fields: [ 'title', 'forumtitle', 'forumid', 'author',
{name: 'replycount', type: 'int'},
{name: 'lastpost', mapping: 'lastpost', type: 'date', dateFormat: 'timestamp'},
'lastposter',
'excerpt'
],
proxy: new Ext.data.ScriptTagProxy({
url: 'http://extjs.com/forum/topics-browse-remote.php'
})
});
store.setDefaultSort('lastpost', 'desc');
var Toolbar=new Ext.PagingToolbar({
pageSize: 5,
store: store,
displayInfo: true,
displayMsg: 'Displaying topics {0} - {1} of {2}',
emptyMsg: "No topics to display",
items:[ '-', {
pressed: true,
enableToggle:true,
text: 'Show Preview',
cls: 'x-btn-text-icon details',
toggleHandler: function(btn, pressed){
var view = grid.getView();
view.showPreview = pressed;
view.refresh();
}
} ]
})
/*var obj=store.sum("replycount",0,4);
Toolbar.addText("数字列的和:"+obj );*/
function renderTopic(value, p, record){
return String.format( '<b><a href="http://extjs.com/forum/showthread.php?t={2}"
target="_blank">{0}</a></b><a href="http://extjs.com/forum/forumdisplay.php?f={3}" target="_blank">{1} Forum</a>',value, record.data.forumtitle, record.id, record.data.forumid); }
function renderLast(value, p, r){
return String.format('{0}<br/>by {1}', value.dateFormat('M j, Y, g:i a'), r.data['lastposter']);
}
function sum(value, p, r){
//Toolbar.addText("数字列的和:" );
//alert(store.sum("replycount",0,4));
return value;
}
var grid = new Ext.grid.GridPanel({
width:700,
height:500,
title:'ExtJS.com - Browse Forums',
store: store,
trackMouseOver:false,
disableSelection:true,
loadMask: true,
columns:[{
id: 'topic',
header: "Topic",
dataIndex: 'title',
width: 420,
renderer: renderTopic,
sortable: true
},{
header: "Author",
dataIndex: 'author',
width: 100,
hidden: true,
sortable: true
},{
header: "Replies",
dataIndex: 'replycount',
width: 70,
align: 'right',
renderer: sum ,
sortable: true
},{
id: 'last',
header: "Last Post",
dataIndex: 'lastpost',
width: 150,
renderer: renderLast,
sortable: true
}],
viewConfig: {
forceFit:true,
enableRowBody:true,
showPreview:true,
getRowClass : function(record, rowIndex, p, store){
var obj=store.sum("replycount",0,4); /*这是数字列的和*/
if(this.showPreview){
p.body = '<p>'+record.data.excerpt+'</p>';
return 'x-grid3-row-expanded';
}
return 'x-grid3-row-collapsed';
}
}, bbar: Toolbar });
grid.render('topic-grid');
store.load({params:{start:0, limit:5}});
Toolbar.addText("数字列的和:" +/*此处要现实数字列的和*/);
});


Extjs中怎样在网格底端添加两个工具条？

在工具栏上增加一个参数，每次加载数据后，将该参数的值更改为你所得到的值（GridPanel显示的数字列的和）