<%@ Register Assembly="AsyncControls" Namespace="DelvingWare.AsyncControls" TagPrefix="dw" %>

<%@ Register Src="~/Controls/AsyncUserControl.ascx" TagName="asyncUserCtrl" TagPrefix="ctr" %>

<dw:AsyncButton runat="server" ID="btMain"
Text="Hide the AsyncUserControl"
OnClick="btMain_Click" 
CssClass="greyButton" />

<ctr:asyncUserCtrl runat="server" ID="asyncUserCtrl" />
<br/>
<i>All the AsyncControl demos are within AsyncUserControls</i>.

using System;
using DelvingWare.AsyncControls;
...
protected void btMain_Click( object sender, AsyncEventArgs ae )
{
    bool visible = asyncUserCtrl.Visible;

    // change the AsyncButton text
    if ( visible )
        btMain.Text = "Show the AsyncUserControl";
    else
        btMain.Text = "Hide the AsyncUserControl";

    // change the AsyncUserControl visibility
    asyncUserCtrl.Visible = !visible;
}

Imports System
Imports DelvingWare.AsyncControls
...

Protected Sub btMain_Click(ByVal sender As Object, ByVal ae As AsyncEventArgs)
    Dim visible As Boolean = asyncUserCtrl.Visible
    ' change the AsyncButton text
    If visible Then
        btMain.Text = "Show the AsyncUserControl"
    Else
        btMain.Text = "Hide the AsyncUserControl"
    End If
    ' change the AsyncUserControl visibility
    asyncUserCtrl.Visible = Not visible
End Sub