In the AAF SDK, when a Component is added to a
Sequence, the Length of the Sequence is updated.
However, if a Sequence contains another Sequence and a
Component is added to the child Sequence, the Length of
the parent Sequence is not updated. It is probably
true that when the length of any Component is updated,
its parent Sequence's Length property is not updated.
This may be known and intended, but, it may not.