function preload_nav_images() {
	// make sure that old browsers don't trip up on image arrays
	if (document.images) {
		//
		//  hover (mouseover) images here
		//
		buttonHover = new Object();
		buttonHover["mn_beloved"] = new Image(148,18);
		buttonHover["mn_beloved"].src = "/images/menu/mn_beloved_hover.gif";
		buttonHover["mn_news"] = new Image(148,18);
		buttonHover["mn_news"].src = "/images/menu/mn_news_hover.gif";
	
		buttonHover["mn_transformations"] = new Image(148,18);
		buttonHover["mn_transformations"].src = "/images/menu/mn_transformations_hover.gif";
		buttonHover["mn_thankyou"] = new Image(148,18);
		buttonHover["mn_thankyou"].src = "/images/menu/mn_thankyou_hover.gif";
		buttonHover["mn_team"] = new Image(148,18);
		buttonHover["mn_team"].src = "/images/menu/mn_team_hover.gif";
		buttonHover["mn_contact"] = new Image(148,18);
		buttonHover["mn_contact"].src = "/images/menu/mn_contact_hover.gif";
		buttonHover["mn_board_of_directors"] = new Image(148,18);
		buttonHover["mn_board_of_directors"].src = "/images/menu/mn_board_of_directors_hover.gif";
		buttonHover["mn_events"] = new Image(148,18);
		buttonHover["mn_events"].src = "/images/menu/mn_events_hover.gif";
		buttonHover["mn_home"] = new Image(148,18);
		buttonHover["mn_home"].src = "/images/menu/mn_home_hover.gif";
		buttonHover["mn_calendar"] = new Image(148,18);
		buttonHover["mn_calendar"].src = "/images/menu/mn_calendar_hover.gif";
		buttonHover["mn_to_volunteer"] = new Image(148,18);
		buttonHover["mn_to_volunteer"].src = "/images/menu/mn_to_volunteer_hover.gif";
		buttonHover["mn_history"] = new Image(148,18);
		buttonHover["mn_history"].src = "/images/menu/mn_history_hover.gif";
		buttonHover["mn_press"] = new Image(148,18);
		buttonHover["mn_press"].src = "/images/menu/mn_press_hover.gif";
		buttonHover["imagine"] = new Image(448,300);
		buttonHover["imagine"].src = "/images/imagine_websplash_top.jpg";
		
		buttonHover["mn_sponsor"] = new Image(148,18);
		buttonHover["mn_sponsor"].src = "/images/menu/mn_sponsor_hover.gif";
		
		
		
	
		//
		//  normal (mouseout) images here
		//
		buttonNormal = new Object();
		buttonNormal["mn_beloved"] = new Image(148,18);
		buttonNormal["mn_beloved"].src = "/images/menu/mn_beloved_norm.gif";
		buttonNormal["mn_news"] = new Image(148,18);
		buttonNormal["mn_news"].src = "/images/menu/mn_news_norm.gif";
		buttonNormal["mn_calendar"] = new Image(148,18);
		buttonNormal["mn_calendar"].src = "/images/menu/mn_calendar_norm.gif";
		buttonNormal["mn_transformations"] = new Image(148,18);
		buttonNormal["mn_transformations"].src = "/images/menu/mn_transformations_norm.gif";
		buttonNormal["mn_thankyou"] = new Image(148,18);
		buttonNormal["mn_thankyou"].src = "/images/menu/mn_thankyou_norm.gif";
		buttonNormal["mn_team"] = new Image(148,18);
		buttonNormal["mn_team"].src = "/images/menu/mn_team_norm.gif";
		buttonNormal["mn_contact"] = new Image(148,18);
		buttonNormal["mn_contact"].src = "/images/menu/mn_contact_norm.gif";
		buttonNormal["mn_board_of_directors"] = new Image(148,18);
		buttonNormal["mn_board_of_directors"].src = "/images/menu/mn_board_of_directors_norm.gif";
		buttonNormal["mn_events"] = new Image(148,18);
		buttonNormal["mn_events"].src = "/images/menu/mn_events_norm.gif";
		buttonNormal["mn_home"] = new Image(148,18);
		buttonNormal["mn_home"].src = "/images/menu/mn_home_norm.gif";
		buttonNormal["mn_calendar"] = new Image(148,18);
		buttonNormal["mn_calendar"].src = "/images/menu/mn_calendar_norm.gif";
		buttonNormal["mn_to_volunteer"] = new Image(148,18);
		buttonNormal["mn_to_volunteer"].src = "/images/menu/mn_to_volunteer_norm.gif";
		buttonNormal["mn_history"] = new Image(148,18);
		buttonNormal["mn_history"].src = "/images/menu/mn_history_norm.gif";
		buttonNormal["mn_press"] = new Image(148,18);
		buttonNormal["mn_press"].src = "/images/menu/mn_press_norm.gif";
		buttonNormal["mn_sponsor"] = new Image(148,18);
		buttonNormal["mn_sponsor"].src = "/images/menu/mn_sponsor_norm.gif";
		
		buttonNormal["imagine"] = new Image(448,300);
		buttonNormal["imagine"].src = "/images/imagine_websplash_2.jpg";
	}
}


function nav_init() {
	
	// get <body> id value (indicates which page we're on)
	var page_id = document.getElementsByTagName('body');
	currentId = page_id[0].getAttribute('id');
	
	// swap image for the page we're on
	switch (currentId) {
		
		case 'home':
			/* no images to set for welcome page */
			break;
		
		case 'beloved':
			set_active_image('mn_beloved');
			break;
			
		case 'news':
			set_active_image('mn_news');
			break;
		
		case 'transformations':
			set_active_image('mn_transformations');
			break;
		
		case 'calendar':
			set_active_image('mn_calendar');	
			break;
			
		case 'thank_you_donors':
			set_active_image('mn_thankyou');	
			break;
			
		case 'team':
			set_active_image('mn_team');	
			break;
			
		case 'contact':
			set_active_image('mn_contact');	
			break;
			
		case 'board_of_directors':
			set_active_image('mn_board_of_directors');	
			break;
			
		case 'events':
			set_active_image('mn_events');	
			break;
			
		case 'to_volunteer':
			set_active_image('mn_to_volunteer');	
			break;
			
		default:
			break;
	}
}



function set_active_image(imageId) {

	// could also use separate array for active images;
	// doesn't have to use buttonHover array
	
	var image = document.getElementById(imageId);
	
	// return previous active image to normal state (if any)
	if (activeId && (imageId != activeId)) {
		var active_img = document.getElementById(activeId);
		active_img.src = buttonNormal[activeId].src;
	}
	
	// show hover version of image for active image
	image.src = buttonHover[imageId].src;
	activeId = imageId;
}



function rollover(evt) {
	if (document.images) {
		// equalize W3C and IE event objects
		evt = (evt) ? evt : ((window.event) ? window.event : null);
		if (evt) {
			//equalize W3C and IE event property
			var elem = (evt.target) ? evt.target : ((evt.srcElement) ? evt.srcElement : null);
			// filter out older browsers (elem=null) and unswappable elements
			if (elem && (elem.className == "rollover")) {
				
				// don't swap image if the image is "active"
				if (elem.id != activeId) {
					
					// let the event type govern state of rollover
					switch (evt.type) {
			
						case "mouseover":
							// switch image to its hover state
							elem.src = buttonHover[elem.id].src;
							break;
							
						case "mouseout":
							// return image to its normal state
							elem.src = buttonNormal[elem.id].src;
							break;
							
						case "click":
							break;
						
						default:
							break;
					}
				}
			}
		}
	}
	return true;
}

function isNotEmpty(elem) {
	var str = elem.value;

	if ((str == null) || (str == '')) {
		return false;
	}
	else {
		return true;
	}
}

function isLengthX(elem, required_length) {
    //var required_length;
	var str = elem.value;
	if (str.length == required_length) {
		return true;
	}
	else {
		return false;
	}
}

function isNumeric(elem) {
	var str = elem.value;
	
	if (isNaN(parseFloat(str))) {
		return false;
	}
	return true
}

function validate_application() {

	var error_message = '';
	var error_message_start = "Please correct the following info: \n\n";
	
    var form = document.getElementById('volunteer_app');
	
	if (!isNotEmpty(form.name_first)) {
		error_message += "FIRST NAME field is blank\n";
	}
	
	if (!isNotEmpty(form.name_last)) {
		error_message += "LAST NAME field is blank\n";
	}
	
	if (!isNotEmpty(form.home_address)) {
		error_message += "HOME ADDRESS field is blank\n";
	}
	
	if (!isNotEmpty(form.home_city)) {
		error_message += "HOME CITY field is blank\n";
	}
	
	if (!isNotEmpty(form.home_state)) {
		error_message += "HOME STATE field is blank\n";
	}
	
	if (!isNotEmpty(form.home_zip)) {
		error_message += "HOME ZIP field is blank\n";
	}
	else if (!isNumeric(form.home_zip)) {
		error_message += "HOME ZIP field is invalid\n";
	}
	
	if (!isNotEmpty(form.phone_home)) {
		error_message += "HOME PHONE field is blank\n";
	}
	
	if (!isNotEmpty(form.email)) {
		error_message += "EMAIL field is blank\n";
	}
	
	if (!isNotEmpty(form.signature)) {
		error_message += "\nPlease fill in the SIGNATURE field\n";
	}
	
	if (error_message == '') {
		// form validated; allow form submission
		return true;
	}
	else {
		// form didn't validate; show errors
		alert(error_message_start + error_message);
		return false;
	}
}

document.onmouseover = rollover;
document.onmouseout = rollover;

var activeId = '';