function getElement(id)
{
	if ( typeof id == 'object' )
		return id;
	
	if (!document.getElementById)
		return;
	var element = document.getElementById(id);
	return element;
}
function hide(id)
{
	change_visibility(id, false);
}

function show(id)
{
	change_visibility(id, true);
}

function change_visibility(id, show)
{
	var element = getElement(id);
	
	if (!element)
		return;
	
	element.style.display = show ? '' : 'none';
}