function screenshot_over(obj) {
  var overlay = obj.getElementsByTagName("div")[0];
  overlay.style.visibility = "visible";
  obj.style.borderColor = "#ff0000";
  moveDown(0);
  function moveDown(top) {
    obj.style.marginTop = top + "px";
    if (top >= 8) return;
    setTimeout(function() { moveDown(top+1) }, 1);
  }
}



function screenshot_out(obj) {
  var overlay = obj.getElementsByTagName("div")[0];
  overlay.style.visibility = "hidden";
  obj.style.borderColor = "";
  moveUp(8);
  function moveUp(top) {
    obj.style.marginTop = top + "px";
    if (top <= 0) return;
    setTimeout(function() { moveUp(top-1) }, 1);
  }
}