Fantastic.  I did write a user control which has a GridView.  This
GridView gets populated with customer names retrieved from the
database.  The customer names in the GridView are made to be
LinkButtons (in template fields).  When such a LinkButton'ed name is
clicked, I want to send the name as a string to the parent control.

Let's call this user control SearchCustomers.ascx.

I followed the example you gave in the link above, and successfully
made the whole thing happen, which kinda excited me.  Thank you.

But, I do not want to show SearchCustomers user control in the parent
page until a button is clicked in the parent page.

I have written a Visible property in SearchCustomers.ascx.cs, like so:

   private bool visible;

   protected void Page_Load(object sender, EventArgs e)
   {
       if (this.visible)
       {
           Panel1.Visible = true;  // Pane1 holds the GridView.
       }
       else
       {
           Panel1.Visible = false;
       }
   }

   public bool Visible
   {
       get
       {
           return this.visible;
       }
       set
       {
           this.visible = value;
       }
   }

In ParentPage.aspx's Page_Load, if I say

            SearchCustomers1.Visible = true;

This control does show up nicely, but if I attempt to set the Visible
property in the button click event handler like so:

protected void btnSearchCustomers_Click(object s, EventArgs e)
{
          SearchCustomers1.Visible = true;
}

The SearchCustomers1 user control does not show up.  I kinda suspect
that it is because it has passed the Page_Load event, so the control
cannot be rendered.  In any case, how do I show/hide a user control
dynamically?  Somehow, I guess this user control has to be recreated /
reloaded, but what do I need to do?

Thank you again if you could share your wisdom.