function slideDropDown(elementID, curheight, final_height, interval, reverse) {
  if(!document.getElementById) return false;
  if(!document.getElementById(elementID)) return false;
  var elem = document.getElementById(elementID);
	
	var speedinc = 20;

  switch(reverse) {
    case 1:
      if(curheight <= final_height) {
        return true;
      }
			
			if(curheight <= speedinc) {
				curheight=final_height;
			}
      
      if(curheight > final_height) {
        curheight-=speedinc;
      }else{
        curheight=final_height;
      }
    break
    default:
      if(curheight >= final_height) {
        return true;
      }
    
      if(curheight < final_height) {
        curheight+=speedinc;
      }else{
        curheight=final_height;
      }
  }
  
  elem.style.height = curheight + "px";
  
  var repeat =
  "slideDropDown('"+elementID+"',"+curheight+","+final_height+","+interval+","+reverse+")";
  movement = setTimeout(repeat,interval);
}