function getHeightBorder(){

	var altezza = document.getElementById('mainContent').offsetHeight;
	
	document.getElementById('ombraSx').style.height=altezza   + 'px';
		
	document.getElementById('ombraDx').style.height=altezza   + 'px';
		
}

function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function changeImages() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}
	}
}

var preloadFlag = false;

function preloadImages2() {
	if (document.images) {
		menu_1_over = newImage("images/headerTop2_btn1_on.jpg");
		menu_2_over = newImage("images/headerTop2_btn2_on.jpg");
		preloadFlag = true;
	}
}