function showTab(id, aTag) {
	var navContainer = document.getElementById("mainnav");
	var navs = navContainer.getElementsByTagName("a");	
	for(var i=0; i<navs.length; i++)
		navs[i].className = "";
	aTag.className="selected";
		
	var tabContainer = document.getElementById("tabs");
	var tabToShow = null;
	var tabs = tabContainer.getElementsByTagName("div");
	for(var i=0; i<tabs.length; i++) {
		if(tabs[i].id.indexOf("tab") > -1) {
			tabs[i].style.display = "none";			
			if(tabs[i].id == "tab" + id)
				tabToShow = tabs[i];
		}
		
	}
	if(tabToShow != null)
		tabToShow.style.display = "block";
}