function hookUpEvents() {
	var portfolioButton = document.getElementById('portfoliobutton');
	var portfolioDropdown = document.getElementById('portfoliodropdown');
	
	if(window.addEventListener) {
		portfolioButton.addEventListener('mouseover', showNavDropdown, true);
		portfolioDropdown.addEventListener('mouseout', hideNavDropdown, true);
	} else {
		portfolioButton.attachEvent('onmouseover', showNavDropdown);
		portfolioDropdown.attachEvent('onmouseout', hideNavDropdown);
	}
}

function showNavDropdown() {
	document.getElementById('portfoliodropdown').style.display = "block";
}

function hideNavDropdown(e) {
	if (!e) var e = window.event;

	var relTarg = e.relatedTarget || e.fromElement;
	
	if(relTarg.nodeName == 'DIV' || relTarg.nodeName == 'IMG' ) {
		document.getElementById('portfoliodropdown').style.display = "none";
	}
	
}