The app list context menu items work just fine if invoked with a key event.
None work when invoked with a mouse event; this is an event dispatch bug.

Oddly, the correct menu item is highlighted on hover, only mouse press is broken.
Also, clicking the app list window while a menu is open closes the menu & window.

I'm debugging services/ui/ws/event_dispatcher.cc and window_manager_state.cc
Any tips or advice here is appreciated, I'm not very familiar with this new code.

Menu item selection occurs on mouse up, but the menu and app list close on mouse down.
So it's not quite an event dispatch issue, I'm looking into the cause of window close.

This isn't shelf related, removing blocker status, but I'll keep looking anyway.

Oh gosh, AppListPresenterDelegateMus::OnPointerEventObserved dismisses the app list for touch/pointer down events on widgets other than the app list, including context menus that it's showing... I'm working on a fix. It was difficult to trace back the widget closing through the WindowTree[Client] and FocusSynchonizer hops, but I'm pretty sure this is the root cause.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a85ad6142b28e405a5ee7d6e6f86b8980115c1a0

commit a85ad6142b28e405a5ee7d6e6f86b8980115c1a0
Author: Mike Wasserman <msw@chromium.org>
Date: Sat Aug 26 00:26:15 2017

mash: Do not dismiss the app list for events on its context menus.

Check for the context menu window as a PointerWatcher target.
(this mash-specific fix checks a complex transient hierarchy)
Add a browser test (TODO: fix shutdown crash in --run-in-mash)

Bug:  730886 
Change-Id: I6d16b98b1394cb3e57d176c7be2b3ea5d83cc0fe
Reviewed-on: https://chromium-review.googlesource.com/636183
Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#497609}
[add] https://crrev.com/a85ad6142b28e405a5ee7d6e6f86b8980115c1a0/chrome/browser/ui/ash/app_list/app_list_browsertest.cc
[delete] https://crrev.com/c1b4adf9c2f60c8dc45bfebf8ba92b319f912b5b/chrome/browser/ui/ash/app_list/app_list_controller_ash_browsertest.cc
[modify] https://crrev.com/a85ad6142b28e405a5ee7d6e6f86b8980115c1a0/chrome/browser/ui/ash/app_list/app_list_presenter_delegate_mus.cc
[modify] https://crrev.com/a85ad6142b28e405a5ee7d6e6f86b8980115c1a0/chrome/test/BUILD.gn