Ho provato usando questo codice ma mi dà errore...vedete un pò :

function TracklistCanc(inForm) {
var i=0
var q=1
while(i<inForm.tracklist.options.length) {
if(inForm.tracklist.options[i].selected){
inForm.tracklist.options[i]= null

//RIORDINO //
while(q < inForm.tracklist.options.length){
trk=inForm.tracklist.options.length + 1 +". " + inForm.tracklist.options[(q)];
inForm.tracklist.options[(q)]= Option(trk,trk,true,true);
q++;
}
}else
i++;
}
}