function moveElement(elementID,final_x,final_y,interval) {
  if (!document.getElementById) return false;
  if (!document.getElementById(elementID)) return false;
  var elem = document.getElementById(elementID);
  if (elem.movement) {
    clearTimeout(elem.movement);
  }
  if (!elem.style.left) {
    elem.style.left = "0px";
  }
  if (!elem.style.top) {
    elem.style.top = "0px";
  }
  var xpos = parseInt(elem.style.left);
  var ypos = parseInt(elem.style.top);
  if (xpos == final_x && ypos == final_y) {
    return true;
  }
  if (xpos < final_x) {
    var dist = Math.ceil((final_x - xpos)/10);
    xpos = xpos + dist;
  }
  if (xpos > final_x) {
    var dist = Math.ceil((xpos - final_x)/10);
    xpos = xpos - dist;
  }
  if (ypos < final_y) {
    var dist = Math.ceil((final_y - ypos)/10);
    ypos = ypos + dist;
  }
  if (ypos > final_y) {
    var dist = Math.ceil((ypos - final_y)/10);
    ypos = ypos - dist;
  }
  elem.style.left = xpos + "px";
  elem.style.top = ypos + "px";
  var repeat = "moveElement('"+elementID+"',"+final_x+","+final_y+","+interval+")";
  elem.movement = setTimeout(repeat,interval);
}



function prepareSlideshow() {
// Make sure the browser understands the DOM methods
  if (!document.getElementsByTagName) return false;
  if (!document.getElementById) return false;
  var left_scroll = document.getElementById("scroll_left");
  left_scroll.onclick = function() {
    moveElement("preview",0,0,10);
  }
  var right_scroll = document.getElementById("scroll_right");
  right_scroll.onclick = function() {
    moveElement("preview",-400,0,10);
  }

}
addLoadEvent(prepareSlideshow);


function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      oldonload();
      func();
    }
  }
}