function ShowImage(img)
{
    if (!document.images)
		return;		
		
    var source = "images/" + img + "CommentBalloon.jpg";
	
	document.images[img].src = source;
	document.images[img].style.visibility = "visible";	
} 

function ClearImage(img)
{
    if (!document.images)
		return;			
		
    document.images[img].src = "";	
	document.images[img].style.visibility = "hidden";		

}