function toggle_visibility(id)
{
	var e = document.getElementById(id);
	if( e.style.display == 'block' )
	{
		e.style.display = 'none';
		document.getElementById('hidebtn').style.backgroundImage = "url('/img/tit_credits_plus.gif')";
	}
	else
	{
		e.style.display = 'block';
		document.getElementById('hidebtn').style.backgroundImage = "url('/img/tit_credits_min.gif')";
	}
}