Problem about change ComboBox's store dynamically

[zhangsir199]

I have a combobox(cmb) editor in gridpanel, cmb's store's data change dynamically:

var dateOperData = [['=', '='], ['<>', '<>'], ['<', '<'], ['>', '>']];
var strOperData = [['=', '='], ['<>', '<>'], ['<', '<'], ['>', '>'], ['like', 'like'], ['in', 'in']];

var setEditor=function(e){
    var oper = Ext.getCmp('edComboOper');
    if(e.record.data.type='date')
        oper.getStore().loadData(dateOperData);
    else
        oper.getStore().loadData(strOperData);
}

...

<ext:gridpanel>
    <listener>
        <beforeEdit Fn="setEditor">
    </listener>
    ...
</ext:gridpanel>

Now, when combobox store data changed, I must click combobox two times, then the dropdown part will display