You have to define a .static.name for each window, or provide a name
when calling addWindows(). See examples here:
https://www.mediawiki.org/wiki/OOjs_UI/Windows/Window_managers
The fact that OOjs UI lets you do this wrong is a bug, though (and we
have some documentation pages that provide bad advice). I filed
https://phabricator.wikimedia.org/T149807 about it.
Also, you should move your definition of ArchiveSection and
CommentInSection classes to top level (they're inside an event handler
now). Right now your code actually redefines these functions/classes
every time the user clicks the buttons. So after the second time the
(for example) "add comment" button is clicked,
`commentInSection.constructor` will no longer be equal to
`CommentInSection`. This could cause hard-to-debug problems in the future.
--
Bartosz Dziewoński