function onSwitch(id) {				
    if(document.getElementById('plank'+id).style.display == 'none') {
        document.getElementById('plank'+id).style.display='block';
        document.getElementById('plus'+id).innerHTML='<img src="/public/img/interface/open.gif" alt =""/>';
    }else{
        document.getElementById('plank'+id).style.display='none';
        document.getElementById('plus'+id).innerHTML='<img src="/public/img/interface/fold.gif" alt =""/>';
    }								
}