function swapImage(arg)
{
    var suffix = '_over';
                    
    var img = arg.id;
    var imgSrc = arg.src;
    
    var imgExtension = imgSrc.substr(imgSrc.length - 4, 4);
    if (imgSrc.substr(imgSrc.length - 8, 5) != '_over')
    {
		var imgOver      = imgSrc.substr(0, imgSrc.length - 4) + suffix + imgExtension;
		document.getElementById(img).src = imgOver;
    }
}

function restoreImage(arg)
{
    var suffix = '_over';
    
    var img = arg.id;
    var imgSrc = arg.src;
    
    var imgExtension = imgSrc.substr(imgSrc.length - 4, 4);
    var imgNormal    = imgSrc.substr(0,imgSrc.length - 9) + imgExtension;
    
    document.getElementById(img).src = imgNormal;
}

function swapMenuImage(objMenuItem, strNewImage)
{
    var img = objMenuItem.id;
    var imgSrc = objMenuItem.src;
    
    if (imgSrc != strNewImage)
    {
		document.getElementById(img).src = strNewImage;
    }
}

function restoreMenuImage(objMenuItem, strOldImage)
{
    var img = objMenuItem.id;
    var imgSrc = objMenuItem.src;
    
    if (imgSrc != strOldImage)
    {
	    document.getElementById(img).src = strOldImage;
	}
}