var old_lay = '';
var old_img = '';
var old_num = '';

function showtab(lay,img,img_num)
{
	if(img_num==old_num)
	{
	  return true;
	}
	if(old_lay != lay)
	{
        if(old_lay != '') {
			old_lay.style.display = 'none';
			old_img.src='images/t_menu'+old_num+'_off_2.jpg';
		}
            
        lay.style.display = 'block';
		img.src='images/t_menu'+img_num+'_on_2.jpg';

        old_lay = lay;
		old_img = img;
		old_num = img_num;
	} 
    else {
        lay.style.display = 'none';
		img.src='images/t_menu'+img_num+'_off_2.jpg';

        old_lay = '';
		old_img = '';
		old_num = '';
    }
}