title: IE 8.0 Escape Key Issue Web Forms
body: <p>One of my QA Team just discovered the following: If you hit ESC twice when on a page containing an update panel with a control inside, if you click on anything else that does a postback, you'll get a System.ArgumentException: Invalid postback or callback argument.  Event validation is enabled using [...] error.</p>
  
  <p>I would like to know more about the default behaviour of the ESC key. And might be interested in hooking up to the event to fire something else when that happens.</p>
  
  <p><strong>Message: Sys.WebForms.PageRequestManagerServerErrorException: Invalid postback or callback argument.  Event validation is enabled using  in configuration or &lt;%@ Page EnableEventValidation="true" %> in a page.  For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them.  If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.</strong></p>
  
  <p><em>Now Actually what is in my page</em> My page just have following components</p>
  
  <ol>
  <li><p>.net4.0 or .net 3.5</p></li>
  <li><p>protected void btnSubmit_OnClick(object sender, EventArgs e){} I have nothing in code behind!!!</p></li>
  <li><p>you can repeat the error by
  a. remove the "" thing
  b. run your website in browser (IE8, compatibility mode also fails)</p></li>
  <li><p>follow the steps below carefully (you should have clicked the submit button twice and pressed Esc key four times after finishing this whole test case)</p></li>
  </ol>
  
  <p>a. click on the textbox to set focus<br>
  b. press Esc key twice in your keyboard (i have tried two seconds per key press, you may try one hour per key press)<br>
  c. click on the submit button<br>
  d. click on the textbox to set focus back<br>
  e. press Esc key twice in your keyboard<br>
  f. click on the submit button  </p>
  
  <p>Any help will be surely appreciated.</p>