怎样获取form表单中的easyui combobox复选取值相对应的id

var width = $(window).width()-80;
var height = $(window).height()-120;
stView_layout = $('#stView_layout').layout({
width: width,
height: height
});
station_view = $('#stationView').window({
title: '测站导航',
left:50,
top:80,
width: width,
modal: false,
shadow: false,
closed: true,
height: height,
onResize:function(w,h){
if(stView_treegrid){
stView_treegrid.treegrid({
width:w-20,
height:h-260
});
}
}
});