var timerlen = 5;
var slideAniLen = 250;

var timerID = new Array();
var startTime = new Array();
var obj = new Array();
var endHeight = new Array();
var moving = new Array();
var dir = new Array();

function slidedown(objname){
  var object = document.getElementById(objname);
  object.style.display == "none";
  if(moving[objname]) {
    return;
  }
  if(object.style.display != "none") {
    return; // cannot slide down something that is already visible
  }
  moving[objname] = true;
  dir[objname] = "down";
  startslide(objname);
}

function slideup(objname){
  if(moving[objname])
  return;
  if(document.getElementById(objname).style.display == "none")
    return; // cannot slide up something that is already hidden
  moving[objname] = true;
  dir[objname] = "up";
  startslide(objname);
}

function startslide(objname){
  obj[objname] = document.getElementById(objname);
  endHeight[objname] = parseInt(obj[objname].style.height);
  startTime[objname] = (new Date()).getTime();
  if(dir[objname] == "down"){
    obj[objname].style.height = "1px";
  }
  obj[objname].style.display = "block";
  timerID[objname] = setInterval('slidetick(\'' + objname + '\');',timerlen);
}

function slidetick(objname){
  var elapsed = (new Date()).getTime() - startTime[objname];
  if (elapsed > slideAniLen)
      endSlide(objname)
  else {
    var d =Math.round(elapsed / slideAniLen * endHeight[objname]);
    if(dir[objname] == "up")
      d = endHeight[objname] - d;
      obj[objname].style.height = d + "px";
    }
  return;
}

function endSlide(objname){
  clearInterval(timerID[objname]);
  if(dir[objname] == "up")
    obj[objname].style.display = "none";
  obj[objname].style.height = endHeight[objname] + "px";
  delete(moving[objname]);
  delete(timerID[objname]);
  delete(startTime[objname]);
  delete(endHeight[objname]);
  delete(obj[objname]);
  delete(dir[objname]);
  return;
}