function nav_over(id){
	if(id != active_main && id != active_sub){
		document.getElementById(id).src = "images/" + id + "_on.gif";
	}
	if(id == "button_02"){
		document.getElementById('button_02_subnav').style.display = "block";
	}else if(id == "button_03"){
		document.getElementById('button_03_subnav').style.display = "block";
	}			
}	
function nav_out(id){
	if(id != active_main && id != active_sub){
		document.getElementById(id).src = "images/" + id + "_off.gif";	
	}	
	if(id == "button_02"){
		hide_subnav("button_02_subnav");
	}else if(id == "button_03"){
		hide_subnav("button_03_subnav");
	}					
}	
function hide_subnav(id){
	document.getElementById(id).style.display = "none";
}
function show_subnav(id){

	document.getElementById(id).style.display = "block";
}