用dialog模式来代替,

修改top,left大小可以调整位置
url="https://www.baidu.com";
$iframe=$("<iframe width='100%' height='100%' scrolling='no' frameborder='0'>");
$iframe.attr("src",url);
var dlg = new FR.Dialog({
       title : 'title',
       height : 100,
       width:400,
       contentHtml : $iframe
});
dlg.doResize({top:100,left:100});
dlg.setVisible(true);

window.form = this.options.form;

var $iframe = $("<iframe id='inp' name='inp' width='100%' height='100%' scrolling='no' frameborder='0'>");

$iframe.attr("src", FR.cjkEncode("${servletURL}?viewlet=doc/Parameter/下拉框数据量大-参数界面子模板.cpt&op=write"));

var o = {

title : "请选择记录项",

width : 460,

height: 350,

};

FR.showDialog(o.title, o.width, o.height, $iframe,o);

$('.fr-core-window').css('top',window.innerHeight-o.height);//子窗口并调整弹窗位置在最下方