function scrollLeft(container){
  if(this.position > 0)
    this.position -= this.thumbsize;
 
  $(container).style.right = this.position+'px';
}

function scrollRight(container){
  if(this.position < (this.width-656)) //656 is the total display width of 4 thumbs
    this.position += this.thumbsize;

  $(container).style.right = this.position+'px';
}