On jquery mobile, how can I auto open the select box when page loads? Like in this sample:

My code:
    <div data-role="fieldcontain">
        <fieldset data-role="controlgroup" data-type="horizontal">
            <select name="select-choice-usa" id="select-choice-usa" size="15">
                <option>USA</option>
                <option selected="selected">EUROPE</option>
                <option>UK</option>
            </select>
            <select name="select-choice-size" id="select-choice-size">
                <option selected="selected">3.5</option>
                <option>4</option>
                <option>4.5</option>
            </select>
        </fieldset>
    </div>
The script I tried:
$('#page1').live("pagecreate", function() {
    $('#select-choice-usa').attr('parent',focus())
});
 
     
     
    