请问我在有atlas的UpdatePanel无刷新符值给一个TEXTBOX控件，却会把里面的FreeTextBox控件变形。

Question

我的FreeTextBox是１。６的。我的代码如下：<atlas:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="True">
</atlas:ScriptManager>
<atlas:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
</ContentTemplate>
    <Triggers>
        <atlas:ControlValueTrigger ControlID="DropDownList1" PropertyName="SelectedValue" />
    </Triggers>
</atlas:UpdatePanel><asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
    <asp:ListItem>a</asp:ListItem>
    <asp:ListItem>b</asp:ListItem>
    <asp:ListItem>c</asp:ListItem>
    <asp:ListItem>d</asp:ListItem>
    <asp:ListItem>e</asp:ListItem>
</asp:DropDownList>
        <FTB:FreeTextBox ID="FreeTextBox1" runat="server">
        </FTB:FreeTextBox>
.CS文件里代码是：using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;public partial class inc_thisform3 : System.Web.UI.UserControl
{
    protected void Page_Load(object sender, EventArgs e)
    {    }    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        Label1.Text = DropDownList1.SelectedValue;
    }
}每当选取DropDownList的值后，FreeTextBox控件就会变形。为什么？如何处理？？？