function changeScreenImages(url_screen,id_screen,count_screen) {
	document.getElementById('screen').src = url_screen;
	for (var i=1;i<=count_screen;i++) {
		if (i == id_screen) {
			document.getElementById('screen_li_'+i).className = 'active';
		} else {
			document.getElementById('screen_li_'+i).className = '';
		}
	}
}

$(document).ready(function() {

    $("ul.dropdown li").dropdown();

});

$.fn.dropdown = function() {

    $(this).hover(function() {
        $(this).addClass("hover");
        $('> .dir', this).addClass("open");
        $('ul:first', this).css('visibility', 'visible');
    }, function() {
        $(this).removeClass("hover");
        $('.open', this).removeClass("open");
        $('ul:first', this).css('visibility', 'hidden');
    });

}