protected function mergeChangesArrays($left, $right)
	{
		$return = $left;

		foreach ($right as $type => $changes)
		{
			if (isset($left[$type]))
			{
				$return[$type] = array_merge($right[$type], $left[$type]);
			}
			else
			{
				$return[$type] = $changes;
			}
		}

		return $return;
	}