function displayIf( id, show ) {
	var element = document.getElementById(id);
	if(!element) {
		alert('Element does not support display');
		return;
	}
	if(typeof(show) == 'undefined') {
		if (element.style.display == 'none' || element.style.display == '') {
			element.style.display = 'block';
		} else {
			element.style.display = 'none';
		}
	} else {
		element.style.display = ( show ? 'block' : 'none' );
	}
}