img = new Image();
var oldImgSrc = "";

/*
* Changes the arrow-state from normal to hoovered.
* Function is called by a mouseover event.
*
* @param the id of the arrow-image, which is going to be changed
*/
function overPfl(id)
{
	img = document.getElementById(id);
	oldImgSrc = img.src;
	img.src = (oldImgSrc.substring(0, oldImgSrc.indexOf(".gif")).concat("_hover.gif"));
}
/*
* Changes the arrow-state from hoovered to normal.
* Function is called by a mouseout event.
*/
function outPfl()
{
	if(oldImgSrc != "")
		img.src = oldImgSrc;
}