private function getRelativeUrl($from, $to)
	{
		$relative = '';
		while (true)
		{
			if ($from === $to)
				return $relative;
			else if ($from === dirname($from))
				return $relative . substr($to, 1);
			if (!strncmp($from . '/', $to, strlen($from) + 1))
				return $relative . substr($to, strlen($from) + 1);

			$from = dirname($from);
			$relative .= '../';
		}
	}