Thanks for your help Wayne!
You really pointed me in the right direction, but, actually, it didn't
help me to solve my problem.
The tutorial you sent me taught how to add toolbar buttons with dropdown
menus to the workbench and I needed to know how to add them to a local
view (extending ViewAction instead of Action).
I don't know why, it seems like ViewAction extension point doesn't have
the "pulldown" tag.
If you or anyone else out there could help me, I would appreciate.