function show(id)
{	
	switchImg(id,"on");	
}

function hide(id)
{
	switchImg(id,"off");
}

function switchImg(id, show)
{
	
	var objImg = document.getElementById("imgRoll");	
	var mapImg = (show == "off") ? "seacloud" : id;		
	objImg.src = "images/nav_map_" + show + "_" + mapImg + ".gif";
	
	if(id != "seacloud") {		
		var objBtn = document.getElementById("btn" + id);
		objBtn.src = "images/nav_buttons_" + show + "_" + id + ".gif";	
		
	}
	
}