function navOverStudents(obj, index) {
	actualObj = getObj(obj);
	dropHideAllStudents();
	var target = getObj(dropStudents[index][0]);
	target.style.display = 'block';
	timeoutIDs.push([ window.setTimeout('dropHideAllStudents();', DROP_DISAPPEAR_MS), obj, index ]);
	obj.src = dropStudents[index][3].src;
}

function navOut(obj, index) {
	// Noop
}

function dropHide(index) {
	var target = getObj(drop[index][0]);
	target.style.display = 'none';
}

function dropHideAllStudents() {
	for(var i = 0; i < dropStudents.length; i++) {
		var target = getObj(dropStudents[i][0]);
		target.style.display = 'none';
	}
	while(timeoutIDs.length > 0) {
		var timeout = timeoutIDs.pop();
		window.clearTimeout(timeout[0]);
		timeout[1].src = dropStudents[timeout[2]][2].src;
	}
}

function mouseEvent(id, image){
    var img = getObj(id);
   img.src = image; 
}


// Array of objects describing the drop menus and their parent images
var dropStudents= [
	[ 'drop_history', 'nav_history', new Image(), new Image() ],
	[ 'drop_people', 'nav_people', new Image(), new Image() ],
	[ 'drop_symbols', 'nav_symbols', new Image(), new Image() ],
	[ 'drop_benefits', 'nav_benefits', new Image(), new Image() ],	
	[ 'drop_personal', 'nav_personal', new Image(), new Image() ]
	
];

dropStudents[0][2].src = '../media/images/nav/history-off.gif';
dropStudents[0][3].src = '../media/images/nav/history-on.gif';
dropStudents[1][2].src = '../media/images/nav/people-off.gif';
dropStudents[1][3].src = '../media/images/nav/people-on.gif';
dropStudents[2][2].src = '../media/images/nav/symbols-off.gif';
dropStudents[2][3].src = '../media/images/nav/symbols-on.gif';
dropStudents[3][2].src = '../media/images/nav/benefits-off.gif';
dropStudents[3][3].src = '../media/images/nav/benefits-on.gif';
dropStudents[4][2].src = '../media/images/nav/personal-off.gif';
dropStudents[4][3].src = '../media/images/nav/personal-on.gif';