隐藏/显示的AsyncFileUpload控件不激发服务器端UploadedComplete事件

我最近在ASP.NET Ajax控件工具包的最新版本(3.0.40412)中遇到了AsyncFileUpload控件。在隐藏的控件中使用它时似乎存在问题,稍后将显示该控件,例如 <div> 带标签 visible=false .

例子:

页代码

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="act" %>
.
.
.
<act:ToolkitScriptManager runat="server" ID="ScriptManager1" />
<asp:UpdatePanel runat="server" ID="upnlFileUpload">
    <ContentTemplate>
        <asp:Button runat="server" ID="btnShowUpload" Text="Show Upload" />
        <div runat="server" id="divUpload" visible="false">
            <act:AsyncFileUpload runat="server" id="ctlFileUpload" />
        </div>
    </ContentTemplate>
</asp:UpdatePanel>

服务器端代码-

Protected Sub ctlFileUpload_UploadedComplete(ByVal sender As Object, ByVal e As AjaxControlToolkit.AsyncFileUploadEventArgs) Handles ctlFileUpload.UploadedComplete

End Sub

Protected Sub btnShowUpload_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnShowUpload.Click
    divUpload.Visible = True
End Sub

我在UploadedComplete事件上有一个断点,但它从不激发。但是,如果将AsyncFileUpload控件从 <DIV & GT; ,使其在初始页面呈现时可见,控件按预期工作。

那么,这是AsynchUploadControl中的一个bug,还是我没有掌握一个基本概念(这是经常发生的)?