function show_sub(from, what) 
{	
	$$('.my_nav').each(function(el)
	{
		el.removeClass('selected');
	});
	
	$(''+from).addClass('selected');
	
	new Ajax('./php/read_file.php', {method: 'post',
									evalScripts: true,
									data: 'w='+what,
									update: 'main'}
									).request();
}