1489545 - Extension menu item in menu on bookmarks toolbar disappears when a submenu is opened

Status: NEW

(WebExtensions :: Frontend, defect, P3)

Description

[Rob Wu [:robwu]]

Attachment: bookmark-menu-item.zip

STR:
1. Load attached extension (creates two menu items for "bookmark" context).
2. Right-click on the browser chrome, and check the "Bookmarks toolbar" to show the bookmarks toolbar.
3. Right-click on the bookmarks toolbar (not a bookmark item) to open a context menu.
4. Hover over the menu item at the bottom (added by the extension).

Expected:
- At step 4, the submenu at the extension menu item should be opened.

Actual:
- At step 4, the menu item disappears.


This happens because the "popupshowing" event from the submenu event bubbles and triggers
https://searchfox.org/mozilla-central/rev/6201a9e0067cf6af118c6a99ae9314b8ceb2c4d5/browser/components/places/content/placesContextMenu.inc.xul#7

and ultimately ends up here (where _shouldShowMenuItem(..) has returns false):
https://searchfox.org/mozilla-central/rev/6201a9e0067cf6af118c6a99ae9314b8ceb2c4d5/browser/components/places/content/controller.js#580

and causes the extension menu item to be disabled & hidden.

I think that the code should either be modified to ignore popupshowing events from submenus, or add logic to not hide extension menus.