title: ASP.NET: RequiredFieldValidator with Multiple TextBoxes in ListView
body: <p>I have a ListView</p>
  
  <pre><code>&lt;asp:ListView ....&gt;
      &lt;asp:TextBox ID="txtComment" ... /&gt;
      &lt;asp:RequiredFieldValidator ID="rfvComment" ControlToValidate="txtComment" ... /&gt;
      &lt;act:ValidatorCalloutExtender ID="vceComment" TargetControlID="rfvComment" ... /&gt;
  
      &lt;asp:Button ID="btnAddComment" ... /&gt;
  
  &lt;/asp:ListView&gt;
  </code></pre>
  
  <p>lets say this ListView creates the following:</p>
  
  <p>TextBox1
  Button1</p>
  
  <p>TextBox2
  Button2</p>
  
  <p>TextBox3
  Button3</p>
  
  <p>If I click on Button2 the RequiredFiledValidator/ValidatorCalloutExtender are applied to TextBox1 instead of TextBox2, if I click on Button3 the RequiredFiledValidator/ValidatorCalloutExtender are applied to TextBox1 as well, I want the RequiredFiledValidator/ValidatorCalloutExtender to apply to the TextBox next to the button, so if I click Button3 I want it to apply to TextBox3.</p>
  
  <p>Does anyone know how can I achieve this?</p>
  
  <p>thank you.</p>