var changing_thumbs = new Array();

function changeThumb(id, i, thumbArray) {
  if (changing_thumbs[id]) {
    (new Image()).src = thumbArray[i];
    document.getElementById("thumb"+id).src = thumbArray[i];
    i++;
    if (i > thumbArray.length - 1) i = 0;
    setTimeout(function() { changeThumb(id, i , thumbArray) }, 600);
  }
}  


function startThumbChange(id, thumbArray) {  
  changing_thumbs[id] = true;
  changeThumb(id, 0, thumbArray);
}

function stopThumbChange(id){
  changing_thumbs[id] = false;
}