Custom Effects MXML declaration gotcha

Creating composit effects such as Parallel and Sequence is easy in Adobe Flex, you can declare it and have children effects directly under it.  For example:

  

  

  ...

The Adobe documentation indicates that the "children" attribute is optional.  So the above declaration is essentially the same as:

  

    

    

    ...

  

However, if I declare a component that inherits from Sequence, I will have to explicitly declare child effects in the "children" tag.  Or the effects would be treated as component declaration instead of child effects.