title: How can I get an UpdatePanel to intercept a CompositeControl's DropDownList
body: <p>I have a CompositeControl that contains a DropDownList.</p>
  
  <p>I have set the AutoPostBack property of the DropDownList to true.</p>
  
  <p>On the page, I have:</p>
  
  <pre><code>&lt;asp:UpdatePanel ID="UpdatePanel" runat="server"&gt;
      &lt;ContentTemplate&gt;
          &lt;MyControl:Control ID="CustomControl" runat="server" /&gt;
      &lt;/ContentTemplate&gt;
  &lt;/asp:UpdatePanel&gt;
  </code></pre>
  
  <p>I've also tried setting <strong>ChildrenAsTriggers="true"</strong> and <strong>UpdateMode="Always,"</strong> but neither resolved the problem.</p>
  
  <p>The problem is that the UpdatePanel is not intercepting the CompositeControl's DropDownList's post back.  (A full POST is being performed when the DropDownList is changed)</p>
  
  <p>How can I get the UpdatePanel to handle the postback?</p>
  
  <p>Thanks!</p>
  
  <p><strong>Edit -- Requested Info</strong></p>
  
  <p>Country and states are both DropDownLists in the CompositeControl.</p>
  
  <pre><code>country.SelectedIndexChanged += new EventHandler(country_SelectedIndexChanged);
  
  protected void country_SelectedIndexChanged(Object sender, EventArgs e)
  {
      states.DataSource = XXX;
      states.DataBind();
  }
  </code></pre>