How to open option list of HTML select tag on onfocus()

$(document).ready(function(){
    $('select').focus(function(){
        $(this).attr("size",$(this).attr("expandto"));
        var x = "select[tabindex='" + (parseInt($(this).attr('tabindex'),10) + 1) + "']";
        $(x).fadeTo(50,0);
    });
    $('select').blur(function(){
        $(this).attr("size",1); 
        var x = "select[tabindex='" + (parseInt($(this).attr('tabindex'),10) + 1) + "']";       
        $(x).fadeTo('fast',1.0);            
    });
});

Link for demo example