一个问题?tabpanel中放checkbox不能正常显示

今天写了一个tabpanel里面放checkbox不能正常显示，改变一下窗口大小才显示出来,我设置的高度也应该够呀

[img]/upload/attachment/59908/319cefde-cac1-3ab3-ab48-2e261bdf4ca3.jpg[/img]

[img]/upload/attachment/59910/3e34c176-05df-37f8-81f0-639a0ec36dab.jpg[/img]


代码
var authtabpanel = new Ext.TabPanel({
activeTab: 0,
renderTo:'roleauthpanel',
frame:true,
defaults:{autoHeight: true},
items:[


{title:'strategyInfo',height:300,items:[
{xtype:'checkbox',height:100,boxLabel: 'Item 3', name: 'cb-auto-3',inputValue:'item3'}
]}
,

{title:'systemInfo',height:300,items:[
{xtype:'checkbox',height:100,boxLabel: 'Item 3', name: 'cb-auto-3',inputValue:'item3'}
]}
,

{title:'baseInfo',height:300,items:[
{xtype:'checkbox',height:100,boxLabel: 'Item 3', name: 'cb-auto-3',inputValue:'item3'}
]}

]
});