Select boxes does not work when editor in ui modal dialog

I have a dialog that contains a ckeditor and a select box. The select box does not work if the dialog is opened with modal:true Try to click on the dropdown menu under the dialog. It works correctly if I switch to source mode but stops working if I switch back to wysiwyg mode and click on the editor.

by danypd69

HTML

<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/smoothness/jquery-ui.css">
<script src="http://code.jquery.com/ui/1.10.3/jquery-ui.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/ckeditor/4.2/ckeditor.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/ckeditor/4.2/adapters/jquery.js"></script>
I have a dialog that contains a ckeditor and a select box.
The select box does not work if the dialog is opened with modal:true
<br>
Try to click on the dropdown menu under the dialog; it works correctly if I switch to source mode but stops working if I switch back to wysiwyg mode and click on the editor.
<br>
    The problem is present on firefox 22, everything works ok in chrome 28

<div id="dialog">
    <textarea id="text"></textarea>
    <select id="sel">
        <option>Click me! I will not open in firefox 22</option>
        <option>Option 1</option>
        <option>Option 2</option>
        <option>Option 3</option>
    </select>
</div>

JavaScript

$(document).ready(function () {
    $("#text").ckeditor(function() {},
      { toolbar: [
		['Bold', 'Italic', '-', 'NumberedList', 'BulletedList', '-', 'Link', 'Unlink', 'Scayt', 'Image', 'Source']
	],
	height: '100px',
	startupFocus: true,
      }) ;
    $("#dialog").dialog( { modal:true, width:600 }) ;
    
});