[eclipse-pmc] API Request: Add handler updateable dropdown menus

["Paul Webster" <paulweb515@xxxxxxxxx>]

As part of the Menu Contribution plan item (bug 154130) I need to request
an API change to allow the active handler that is associated with a
drop-down menu contribution to replace the dropdown menu.

GOALS/BENEFITS:
- Support RetargetAction functionality for navigate actions: next,
previous, next annotation, previous annotation, etc.

CORRESPONDING BUG:
[Contributions] Allow the active handler to update the dropdown menu
https://bugs.eclipse.org/bugs/show_bug.cgi?id=176182

RISKS:
- no risks

PERFORMANCE IMPACTS:
- no performance impact

--
Paul Webster
Hi floor.  Make me a sammich! - GIR