title: Asp.Net page with Ajax reload the whole page everytime, why?
body: <p>Here is a snippet that doesn't work:</p>
  
  <pre><code>&lt;form id="form1" runat="server"&gt;
  
      &lt;div&gt;
          This is the time :
          &lt;br /&gt;
          &lt;asp:ScriptManager ID="ScriptManager1" runat="server"&gt;&lt;/asp:ScriptManager&gt;
          &lt;asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="conditional" ChildrenAsTriggers="false"&gt;
  
              &lt;ContentTemplate&gt;
                  &lt;asp:TextBox ID="txtDate" runat="server"&gt;&lt;/asp:TextBox&gt;
             &lt;/ContentTemplate&gt;
  
             &lt;Triggers&gt;
                  &lt;asp:AsyncPostBackTrigger  ControlID="btnRefresh"/&gt;
             &lt;/Triggers&gt;
  
          &lt;/asp:UpdatePanel&gt;
  
          &lt;br /&gt;
          &lt;asp:Button ID="btnRefresh" runat="server" text="Refresh" OnClick="btnRefresh_Click"/&gt;
      &lt;/div&gt;
  
  &lt;/form&gt;
  </code></pre>
  
  <p>In the code behind:</p>
  
  <pre><code> protected void Page_Load(object sender, EventArgs e)
    {
  
       Clock c = new Clock();
       string display = c.GetCurrentTime().ToLongTimeString();
       this.Title = display;
       this.txtDate.Text = display;
  
    }
  
    protected void btnRefresh_Click(object sender, EventArgs e)
    {
       Clock c = new Clock();
       string display = c.GetCurrentTime().ToLongTimeString();
       this.txtDate.Text = display;
    }
  </code></pre>
  
  <p>Why does the page reload and not just the UpdatePanel?</p>