popup control linkbutton prevent postback
<p>I am using a popup control with a link button inside that is used to close the popup. The problem is that the link button (or image button in the code below) is causing a full postback which is not intended. Can anyone help? below is the code.</p>

<pre><code>  &lt;asp:PopupControlExtender ID="PopupControlLogin" BehaviorID="logpop" Position="Bottom"
    TargetControlID="myLogin" PopupControlID="PanelLogin" runat="server"&gt;
&lt;/asp:PopupControlExtender&gt;
&lt;asp:Panel ID="PanelLogin" Style="position: absolute; display: none;" runat="server"&gt;
    &lt;div style="border: solid 1px #808080; border-width: 1px 0px;"&gt;
        &lt;div style="background: url(images/sprite.png) repeat-x 0px -200px;"&gt;
            &lt;asp:Label ID="Label2" runat="server" Style="font-weight: bold;" Text="Login" /&gt;
            &lt;asp:ImageButton ID="ImageButton1" Style="background: url(images/sprite.png) no-repeat 0px -300px;"
                OnClientClick="$find('logpop').hide(); return false;" runat="server" /&gt;
        &lt;/div&gt;
        &lt;div style="background-color: #f2f2f2; width: 300px; height: 150px;"&gt;
            My Content
        &lt;/div&gt;
    &lt;/div&gt;
&lt;/asp:Panel&gt;
</code></pre>
