function dealSelectAccount(sender) {
        var result = window.showModalDialog("ProjectTypeList.aspx", "", "dialogWidth:540px;dialogHeight:255px;dialogLeft:300px;dialogTop:250px;center:yes;help=no;resizable:no;status:no;scroll=yes");


        alert(result);

protected void btn1_Click(object sender, EventArgs e)
        {
            for (int i = 0; i < this.treeList.Nodes.Count;i++ )
            {
                if(treeList.CheckedNodes[i].Checked==true)
                {
                    Session["ID"] = treeList.CheckedNodes[i].Value.ToString();
                    Session["NAME"] = treeList.CheckedNodes[i].Text.ToString();
                    string tmp = Session["NAME"].ToString();
                    Response.Write(" <Script language='JavaScript'> window.opener=null;window.open('about:blank','_self');window.returnValue = '" + Session["NAME"].ToString() + "';window.close();</Script>");
                    break;
                }
            }
         }

页面B：点击B上的（html）img执行function RetrunVal()
function RetrunVal()
{
    var obj = window.dialogArguments;
                   obj.value1=document.form1.ddlB.value;
                   window.returnValue = obj;
                   window.close();
}
页面A:在页面A加入TextBox1

function OpenDialog(Url)
{
  var t1;
var obj=showModalDialog(url,window,"dialogHeight:200px;dialogWidth:500px"); 
if(obj != undefined)        
  {              t1= obj.value1;              
eval("form1.TextBox1.value='"+TextBox1Name+"'");              
eval("form1.TextBox1.blur()");          }
}