var subs_array = new Array("sub1","sub2","sub3");

function displaySubs(the_sub){
	if (document.getElementById(the_sub).style.display==""){
		document.getElementById(the_sub).style.display = "none";
	return
	}
	for (i=0;i<subs_array.length;i++){
		var my_sub = document.getElementById(subs_array[i]);
		my_sub.style.display = "none";
	}
	document.getElementById(the_sub).style.display = "";
}