title: ASP.NET Textbox DropDownExtender
body: <p>How to get the value from the dropdown to return to the TextBox?
  The following does not work. You can select the item from list though.</p>
  
  <pre><code>&lt;body&gt;
  &lt;form id="form1" runat="server"&gt;
  &lt;script type="text/javascript"&gt;
      function pageLoad() {
          //Same Width
          $get('ListBox1').style.width = $get('TextBox1').clientWidth;
      }
  &lt;/script&gt;
  &lt;ajax:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server"&gt;
  &lt;/ajax:ToolkitScriptManager&gt;
  &lt;div&gt;
      &lt;asp:TextBox ID="TextBox1" runat="server"&gt;&lt;/asp:TextBox&gt;
      &lt;ajax:DropDownExtender ID="TextBox1_DropDownExtender" DropDownControlID="ListBox1"
          runat="server" DynamicServicePath="" Enabled="True" TargetControlID="TextBox1"
          HighlightBackColor="WhiteSmoke"&gt;
      &lt;/ajax:DropDownExtender&gt;
  &lt;/div&gt;
  &lt;asp:ListBox ID="ListBox1" runat="server" AutoPostBack="True"&gt;
      &lt;asp:ListItem&gt;Item 1&lt;/asp:ListItem&gt;
      &lt;asp:ListItem&gt;Item 2&lt;/asp:ListItem&gt;
      &lt;asp:ListItem&gt;Item 3&lt;/asp:ListItem&gt;
  &lt;/asp:ListBox&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>
  </p>