title: How can I prevent all update panels reloading when I click a button in one of them?
body: <p>I've got a webform with two update panels:</p>
  
  <pre><code>&lt;asp:ScriptManager ID="ScriptManager1" runat="server" ScriptMode="Release"&gt;
      &lt;/asp:ScriptManager&gt;
  
  &lt;p&gt;
      &lt;asp:UpdatePanel ID="upl1" runat="server"&gt;
          &lt;ContentTemplate&gt;
              &lt;asp:Button runat="server" ID="btn1" Text="Button1" /&gt;
          &lt;/ContentTemplate&gt;
      &lt;/asp:UpdatePanel&gt;
  
      &lt;asp:UpdatePanel ID="upl2" runat="server"&gt;
          &lt;ContentTemplate&gt;
              &lt;asp:Button runat="server" id="btn2" Text="Button2" /&gt;
          &lt;/ContentTemplate&gt;
      &lt;/asp:UpdatePanel&gt;
  &lt;/p&gt;
  </code></pre>
  
  <p>If I click <code>btn1</code>, then the load event of <code>upl2</code> is triggered, as well as <code>upl1</code>.</p>
  
  <p>I would expect only <code>upl1</code> to be loaded, since this is the update panel that contains the button.</p>
  
  <p>Why isn't this happening, and how can I make it happen?</p>