function checking(idCheckCanal){
if(document.getElementById(idCheckCanal).checked){
    document.getElementById(idCheckCanal).checked=false;
}else{
    document.getElementById(idCheckCanal).checked=true;
}    
}

function move_up(current){
    var capa=document.getElementById(current);
    alert(capa);
    alert(capa.style.top);
    alert(capa.style.top.substr(0,capa.style.top.length-2));
    var posicion = parseInt(capa.style.top.substr(0,capa.style.top.length-2)); 
    alert(posicion);
    posicion=posicion-56;
    capa.style.top=posicion +'px';
}

function move_down(current){
    var capa=document.getElementById(current);
    alert(capa);
    alert(capa.style.top);
    alert(capa.style.top.substr(0,capa.style.top.length-2));
    var posicion = parseInt(capa.style.top.substr(0,capa.style.top.length-2)); 
    alert(posicion);
    posicion=posicion+56;
    capa.style.top=posicion +'px';
}