JavaScript: How to reference user control inside content page?
<p>This is structure I have:</p>

<p>Master page -> Content page -> User control -> Telerik grid with its context menu, hidden field.</p>

<p>This means: Master page contains content page, content page contains user control, user control contains Telerik grid with its context menu and hidden field.</p>

<p>I open popup window by clicking option in Telerik grid's context menu. After I choose some option in combo box in that popup window I press OK and close it. But I don't know how to reference opener that should be user control with Telerik grid and hidden field. I want to set hidden field to some value.</p>

<p>This is JavaScript code I use:</p>

<pre><code>&lt;script language="javascript" type="text/javascript"&gt;
    function ReturnValue() {
        var choice = document.getElementById("DropDownList1").value;
        if ((window.opener != null) &amp;&amp; (!window.opener.closed)) {
            window.opener.document.getElementById("HiddenField1").value = choice;
        }
        window.close();
    }
&lt;/script&gt;
</code></pre>

<p>But, it fails on this line because opener is master page:</p>

<pre><code>window.opener.document.getElementById("HiddenField1").value = choice;
</code></pre>

<p>So, how can I make it work?</p>
