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 preloadImages() {
	if (document.images) {
		btn_presentation_over = newImage("res/btn_presentation_over.gif");
		btn_presentation_down = newImage("res/btn_presentation_down.gif");
		btn_securite_over = newImage("res/btn_securite_over.gif");
		btn_securite_down = newImage("res/btn_securite_down.gif");
		btn_abonnement_over = newImage("res/btn_abonnement_over.gif");
		btn_abonnement_down = newImage("res/btn_abonnement_down.gif");
		btn_assistance_over = newImage("res/btn_assistance_over.gif");
		btn_assistance_down = newImage("res/btn_assistance_down.gif");
		preloadFlag = true;
	}
}