var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		pre_n1_over = newImage('../images/n1-over.gif');
		pre_n2_over = newImage('../images/n2-over.gif');
		pre_n3_over = newImage('../images/n3-over.gif');
		pre_n4_over = newImage('../images/n4-over.gif');
		pre_n5_over = newImage('../images/n5-over.gif');
		pre_n6_over = newImage('../images/n6-over.gif');
		pre_n7_over = newImage('../images/n7-over.gif');
		preloadFlag = true;
	}
}
function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}
function init() {
	preloadImages();
	var mainMenuLinks = document.getElementById('main-menu').getElementsByTagName('img');
	// get the current page name
	var whichPage = window.location.href;
	var pageUrlArr = whichPage.split("/");
	var pageName = pageUrlArr[pageUrlArr.length -1].replace( ".shtml", "" );
	for ( i = 0; i < mainMenuLinks.length; i++ ) {
		// turn on menu link for current page
		if ( mainMenuLinks[i].getAttribute("id") === pageName ) {
			tmpSrc = mainMenuLinks[i].getAttribute("src");
			tmpSrc = tmpSrc.replace( ".gif", "-over.gif" );
			mainMenuLinks[i].setAttribute("src", tmpSrc);
			currentPageIndex = i;
		} else { // add rollover events
			mainMenuLinks[i].onmouseover = function() {
				tmpSrc = this.src;
				tmpSrc = tmpSrc.replace( ".gif", "-over.gif" );
				this.src= tmpSrc;
			}
			mainMenuLinks[i].onmouseout = function() {
				tmpSrc = this.src;
				tmpSrc = tmpSrc.replace( "-over.gif", ".gif" );
				this.src= tmpSrc;
			}
		}
	} // end for loop
}