var current_sub='';	
function hideDivs(sub_menu){
	if(current_sub!='' && current_sub!=sub_menu){
		document.getElementById(current_sub).style.visibility = "hidden";
		current_sub='';
	}			
}
function show(sub_menu){
	hideDivs(sub_menu);
	current_sub=sub_menu;
	document.getElementById(sub_menu).style.visibility = "visible";
}
function hide() {
	if(current_sub!='')
		document.getElementById(current_sub).style.visibility = "hidden";
}