title: How to make BalloonPopupExtender appears and disappears with Tab key from the keyboard?
body: <p>I am a new ASP.NET developer and trying to use ASP.NET Ajax BallouPopupExtender with the form that I have. I wrote the code and it works well but what I want now is the following:
  I have 4 TextBoxs aligned besides each other. Now the Ajax BalloonPopupExtender control will only work if the user clicks on each TextBox using the mouse. However, if the users uses the Tab key from his keyboard to fill these TextBoxs, this BalloonPopupExtender will not be appeared. 
  <strong>So how to make it works with Tab key?</strong></p>
  
  <p>My Code:</p>
  
  <pre><code>&lt;ajaxToolkit:BalloonPopupExtender ID="BalloonPopupExtender1" runat="server"
                                              TargetControlID="CorrectAnswerTextBox" BalloonPopupControlID="pnlBallon"
                                              Position="BottomRight" BalloonStyle="Cloud" BalloonSize="Small" 
                                              CustomCssUrl="ballonPopupStyle" CustomClassName="oval" UseShadow="true" ScrollBars="Auto" 
                                              DisplayOnMouseOver="true" DisplayOnFocus="false" DisplayOnClick="true"&gt;
                  &lt;/ajaxToolkit:BalloonPopupExtender&gt;
  
                  &lt;asp:Panel ID="pnlBallon" runat="server"&gt;
                      Test TEST
                  &lt;/asp:Panel&gt;
  </code></pre>