var pageChanged = false;

// return a reference to a DOM element by ID
function e(id) {
	return document.getElementById(id);
}

// return a reference to a form element by name (within the first form and within the action array)
function f(name) {
	if (typeof(document.forms[0].elements[name]) != 'undefined') return document.forms[0].elements[name];
	else return {checked:0, disabled:1, selectedIndex:0, options:{0:{value:'', text:''}}};
}

// return or set the display property of a DOM element by ID
function d(id, display) {
	if (e(id) == null) return false;
	if (arguments.length == 1) return (e(id).style.display == 'none' ? false : true);
	else e(id).style.display = display ? '' : 'none';
}

// clear the value property of a DOM element by ID
function c(id, clear) {
	if (e(id) == null) return false;
	if (clear == true) e(id).value = '';
}

// toggle an element by ID
function toggle(elementID) {
	e(elementID).style.display = e(elementID).style.display == 'none' ? '' : 'none';
}
function toggleImage(elementID) {
	var moreInfo = 'moreInformation' + elementID;
	var moreInfoLink = 'moreInformationImage' + elementID;
	if (e(moreInfo).style.display == 'none') {
		e(moreInfo).style.display = ''
		e(moreInfoLink).src = 'images/button-down.gif';
	}
	else {
		e(moreInfo).style.display = 'none';
		e(moreInfoLink).src = 'images/button.gif';
	}

}
function toggleCategory(categoryID,rowCount) {
	for (i = 0; i < rowCount; i++) {
		var categoryRow = 'category' + categoryID + i;
		toggle(categoryRow);
	}
	var categoryReturnToTopLink = 'returnToTop' + categoryID;
	toggle(categoryReturnToTopLink);
}

// keep track of whether or not the page has changed
pageChanged = false;
// register that the page has changed
function registerFormChanged() {
	pageChanged = true;
}
// confirm a link click if the page has changed
function confirmLink() {
	if (pageChanged) return confirm("You have not saved your changes to this page. Press \"OK\" to discard your changes and continue, \"Cancel\" to return to the page.");
	return true;
}