var calques = new Array ();

function hide_all()
{
	for (i=0;i<4;i++)
	{
		category = document.getElementById(calques[i]);
		if (category)
			category.style.visibility='hidden';
	}
}
function show(nom)
{
	hide_all();
	category = document.getElementById(nom);
	if (category)
		category.style.visibility='visible';
}