var numMenus = 7; //the number of tabs you have

function getStyleObject(objectId) {
    if(document.getElementById && document.getElementById(objectId)) {
	return document.getElementById(objectId).style;
    } else if (document.all && document.all(objectId)) {
	return document.all(objectId).style;
    } else if (document.layers && document.layers[objectId]) {
	return document.layers[objectId];
    } else {
	return false;
    }
} 

function showMenu(menuNumber) {
    hideAllMenus();
    var menuId = 'menu' + menuNumber;
    if(changeObjectVisibility(menuId, 'visible')) {
	var menuTitle = getStyleObject('menuTitle' + menuNumber);
	changeTab(menuNumber);
	return true;
    } else {
	return false;
    }
}

function changeObjectVisibility(objectId, newVisibility) {
    var styleObject = getStyleObject(objectId);
    if(styleObject) {
	styleObject.visibility = newVisibility;
	var menuTitle = getStyleObject('menuTitle' + counter);
	return true;
    } else {
	return false;
    }
} 

function changeTab(menuNumber) {
	var tabId = 'tab' + menuNumber;
	var layerId = 'menuTitle' + menuNumber;
	
	if (document.layers)   {	
		for(counter = 1; counter <= numMenus; counter++) {
			document[('menuTitle' + counter)].document[('tab' + counter)].src = "/images/book_a_trip/tool/" + ('tab' + counter) +"-off.gif";
    		}
	 	document[layerId].document[tabId].src = "/images/book_a_trip/tool/" + tabId +"-on.gif";
	} else {
		for(counter = 1; counter <= numMenus; counter++) {
			document[('tab' + counter)].src = "/images/book_a_trip/tool/" + ('tab' + counter) +"-off.gif";
    		}
	 	document[tabId].src = "/images/book_a_trip/tool/" + tabId +"-on.gif";
	}
}
		
function hideAllMenus() {
    for(counter = 1; counter <= numMenus; counter++) {
	changeObjectVisibility('menu' + counter, 'hidden');
    }
}