var moverElement = null;
var moverHeight = 0;
var moverFrameHeight = 0;
var moverHandle = null;
var moverRefresh = 30;
var moverSpace = 4;
var moverDirection = null;

function initMover(_element,_direction) {
	if(!moverElement) {
		moverElement = document.getElementById(_element);
   }

   moverHeight = moverElement.offsetHeight;
   moverFrameHeight = moverElement.parentNode.offsetHeight;

   if(moverHeight <= moverFrameHeight) {
   	return;
   }

   moverDirection = _direction;

   if(!moverHandle) {
	   moverHandle = window.setInterval("moveMover()",moverRefresh);
   }
}

function moveMover() {
	offset = moverElement.style.top.substr(0,moverElement.style.top.length-2)*1;
   offset = offset + (moverDirection == 'up' ? moverSpace : -1 * moverSpace);

   if(offset * -1 + moverFrameHeight >= moverHeight) {
   	offset = moverFrameHeight-moverHeight;
   } else if(offset >= 0) {
   	offset = 0;
   }

	moverElement.style.top = offset + "px";
}

function stopMover() {
	moverDirection = null;
   moverElement = null;
   window.clearInterval(moverHandle);
   moverHandle = null;
}