Description Nicholas Bennett 2005-10-20 13:52:28 EDT

When an element has a settable container feature, undo/redo behavior of an Add 
to a container element produces incorrect results.  In particular, when redo 
is attempted, the element is appended to the end of the containment collection 
and then moved some seemingly arbitrary amount upwards.  The original index of 
this element is not respected or restored on redo of the add.

Setup of scenario (using org.eclipse.uml2 as an example):

1. Create an Interaction
2. Add multiple CombinedFragments the fragments collection of the Interaction.
3. Add an InteractionOccurrence to the beginning of the fragments collection.
4. Undo/redo the add in step 3.

Notice the InteractionOccurrence is not replaced at the beginning of the 
fragments collection as expected.

This seems to be because MSL is receiving events for both the set of the 
enclosingInteraction feature of the InteractionOccurrence and for the add of 
the InteractionOccurrence to the fragments collection of the Interaction.  
When the add is redone, the redo of the Set appends the InteractionOccurrence 
to the fragments list.  The redo of the add to the fragments collection is 
then executed.