How Does ASP.NET Knows Which Button Caused a PostBack?
<p>I'm using ASP.NET 4 to create a page with elements that are used in a <a href="http://docs.jquery.com/UI/Sortable" rel="nofollow">jQuery UI Sortable plugin</a>.</p>

<p>All of these elements contain a button (implemented as a submit button) with the name <code>SubmitButton</code>. All but one of these buttons are hidden in the page's Load event. But if I drag the element to another position, and then submit the page using that button, ASP.NET gets confused.</p>

<p>ASP.NET thinks I've clicked a different button, one that wasn't even visible on the page, but is associated with content at the position where the clicked button was before the move. (If I don't move the element, it works fine.)</p>

<p>I can't seem to determine how this is happening. As I understand it, ASP.NET knows which submit button caused a postback because the button's name and value is included in the postback data. (<code>__EVENTTARGET</code> plays no role here and is empty.) So how can it think a different button submitted the page?</p>

<p>How could ASP.NET get confused about which button submitted the page?</p>

<p><em>(Sorry, it's not possible to put this page on a public website.)</em></p>
