Event.observe(window, 'load', function() {
    
    $('thumbnails').select('div').each(function(item) {
        
        item.observe('click', function() {
            chooseThumbnail(item);
        });
        if ($(item).getAttribute('class') == 'thumb-item active') {
            chooseThumbnail(item);
        }
    });
	
    var someActive = false;
    $('.item active').each(function(item) {
        chooseThumbnail(item);
        someActive = true;
    });
	
    if (someActive == false) {
        chooseThumbnail($('thumbnails').select('div').first());
    }
	
});

function chooseThumbnail(item) {

			$('thumbnails').select('.active').each(function(s) {
				$(s).removeClassName('active');
			});
			
			$(item).addClassName('active');
			var imgSrc = $(item).down('img').src.sub('/small/','/fullsize/');
			$('productLargeImage').writeAttribute('src',imgSrc);

}