var colModel = new Ext.grid.ColumnModel({
      columns: [ columns here...]
})

var grid = new Ext.Ext.grid.GridPanel({
   store: store,loadMask: true,autoExpandColumn: 'itemDescription',stripeRows: true,colModel: colModel
})

var form = new Ext.FormPanel({
   labelWidth: 150,bodyStyle: 'padding:2px 5px;',autoScroll: true,items:[
     new Ext.form.FieldSet({
       layout: 'fit',collapsible: true,height:300,items: [
            grid 
       ]
     }
   ]
})

一旦窗口调整大小,网格不会改变其宽度…
有什么想法吗？？？