/**
 * Creates a new image object in cache for the preloadImages() function below.
 */
function newImage (arg) {
	if (document.images) {
		var rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}
	
/**
 * Swaps the image named in the first argument with the one in the second.
 */
function changeImages () {
	if (document.images && (preloadFlag == true)) {
		for (var i = 0; i < changeImages.arguments.length; i += 2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i + 1];
		}
	}
}
	
/**
 * Preloads the horizontal navigation images onLoad of the page so that there is
 * no initial delay when the user rolls over them.
 */
var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		var nav_roomvision_off = newImage('img/nav-roomvision-black.gif');
		var nav_roomvision_on = newImage('img/nav-roomvision-gray.gif');
		var nav_login_off = newImage('img/nav-login-black.gif');
		var nav_login_on = newImage('img/nav-login-gray.gif');
		var nav_project_off = newImage('img/nav-project-black.gif');
		var nav_project_on = newImage('img/nav-project-gray.gif');
		var nav_myroom_off = newImage('img/nav-myroom-black.gif');
		var nav_myroom_on = newImage('img/nav-myroom-gray.gif');
		var nav_select_off = newImage('img/nav-select-black.gif');
		var nav_select_on = newImage('img/nav-select-gray.gif');
		var nav_close_off = newImage('img/nav-close-black.gif');
		var nav_close_on = newImage('img/nav-close-gray.gif');
		preloadFlag = true;
	}
}

/**
 * Jumps to the selected item in the dropdown list.
 */
function jumpURL (dropdown) {
	location.href = dropdown.options[dropdown.selectedIndex].value;
}

/**
 * Jumps to the selected item in the dropdown list.
 */
function jumpURLpage (prefix, dropdown) {
	try {
		location.href = prefix + dropdown.options[dropdown.selectedIndex].value;
	} catch (e) {
		alert('Please select a content item.');
	}
}

/**
 * Prompts the user as to whether he really wants to close RoomVision.
 */
function confirmClose () {
	if (!confirm('Are you sure you want to close RoomVision?')) {
		return;
	}
	self.close();
}

/**
 * Prompts the user as to whether he really wants to close the Purgatory window.
 */
function confirmClosePurg () {
	if (!confirm('Are you sure you want to close this window?')) {
		return;
	}
	self.close();
}