var lastTab = "";

function showChunk(chunkName) {
	if(lastTab != "" && jQuery("div#divlayer_"+lastTab) != null) {
		jQuery("div#divlayer_"+lastTab).hide();
	}
	lastTab 											= chunkName;
	if(jQuery("div#divlayer_"+chunkName) != null) {
		jQuery("div#divlayer_"+chunkName).show();
	}
	if (chunkName == "updates") {
		jQuery('img#updates').attr('src','/images/nav/updates_on.gif');
		jQuery('img#archives').attr('src','/images/nav/archives_off.gif');
		jQuery('img#doc').attr('src','/images/nav/doc_off.gif');
	}
	if (chunkName == "archives") {
		jQuery('img#updates').attr('src','/images/nav/updates_off.gif');
		jQuery('img#archives').attr('src','/images/nav/archives_on.gif');
		jQuery('img#doc').attr('src','/images/nav/doc_off.gif');
	}
	if (chunkName == "doc") {
		jQuery('img#updates').attr('src','/images/nav/updates_off.gif');
		jQuery('img#archives').attr('src','/images/nav/archives_off.gif');
		jQuery('img#doc').attr('src','/images/nav/doc_on.gif');
	}
}