function changespin(id,amount) {
   edt = getObj(id);
   if (!isNumber(edt.value)) {
      edt.value = '0';
   } else {
     var newval = amount + parseInt(edt.value);
     if (newval < 0) {
       newval = 0;
     }
     if (edt.value != newval) {
        edt.value = newval;
        spinchanged(id);
     }
   }
 }