function getElementById ( id ) {
	return document.getElementById( id );
}
function getChildrenByTagName ( elem, tag ) {
	return elem.getElementsByTagName( tag );
}
function getEventSource ( e ) {
	// get the source element in a cross-browser way
	if ( window.event ) { 
		return window.event.srcElement;
	} 
	else if ( e.target ) { 
		return e.target;
	} 
	return;
}