C# 更新进度GIF图像可以'；当我单击Modal pop Extender中的按钮时，将无法显示

我有一个问题，当我单击Modal Pop Extender中的按钮时，无法显示更新进度GIF图像

Aspx代码为：

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdateProgress ID="UpdateProgress1" runat="server" AssociatedUpdatePanelID="UpdatePanel1">
    <ProgressTemplate>
        <img src="ajax-loader.gif"  />
    </ProgressTemplate>
</asp:UpdateProgress>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <asp:Button ID="Button2" runat="server" Text="Button" />
        <asp:Panel ID="Panel1" runat="server">
            <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
        </asp:Panel>
        <asp:ModalPopupExtender PopupControlID="Panel1" TargetControlID="Button2" ID="mpeConfirm"
            runat="server">
        </asp:ModalPopupExtender>
    </ContentTemplate>
</asp:UpdatePanel>

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在谷歌搜索一天后。我做到了：）。解决办法很简单，真的很棒

首先，我在设计器中做了一个简单的修改。我刚刚将更新面板移动到Modalpop Extender面板控件中，如下所示：

<asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <asp:UpdateProgress ID="UpdateProgress1" runat="server">
        <ProgressTemplate>
            <img src="ajax-loader.gif" />
        </ProgressTemplate>
    </asp:UpdateProgress>
    <asp:Button ID="Button2" runat="server" Text="Button" />
    <asp:Panel ID="Panel1" runat="server">
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <asp:Button ID="Button1" runat="server" Text="panel" OnClick="Button1_Click" />
            </ContentTemplate>
        </asp:UpdatePanel>
    </asp:Panel>
    <asp:ModalPopupExtender ID="modalExtender" runat="server" PopupControlID="Panel1"
        TargetControlID="Button2">
    </asp:ModalPopupExtender>

非常感谢“Hitesh Sharma”和他通过这个有用的链接对类似问题的回答：

<asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <asp:UpdateProgress ID="UpdateProgress1" runat="server">
        <ProgressTemplate>
            <img src="ajax-loader.gif" />
        </ProgressTemplate>
    </asp:UpdateProgress>
    <asp:Button ID="Button2" runat="server" Text="Button" />
    <asp:Panel ID="Panel1" runat="server">
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <asp:Button ID="Button1" runat="server" Text="panel" OnClick="Button1_Click" />
            </ContentTemplate>
        </asp:UpdatePanel>
    </asp:Panel>
    <asp:ModalPopupExtender ID="modalExtender" runat="server" PopupControlID="Panel1"
        TargetControlID="Button2">
    </asp:ModalPopupExtender>

protected void Button1_Click(object sender, EventArgs e)
{
    string script ="document.getElementById(";
    script += "'";
    script+=Panel1.ClientID;
    script += "'";
    script+=").style.display='none';";
    ScriptManager.RegisterStartupScript(this, this.GetType(), "A",script , true);
    System.Threading.Thread.Sleep(2000);

}