function $(id) {
	return document.getElementById(id);
}

function trackChange(obj, initial_state) {
	if (obj.value == initial_state) {
		obj.value = '';
	} 
	else
	if (obj.value == '') {
		obj.value = initial_state;
	}
}

function toggleBlockVisibility(id) {
	var t = $(id);
	t.style.display = (t.style.display == 'block' ? 'none' : 'block');
	return false;
}