User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0 Build ID: 20170808114032 Steps to reproduce: As I described in bug 1367160#c7 the contextMenus API can not be used in the sidebar. Clicking the menuitem will cause a TypeError. I think "sidebar" context is needed, just like "tab" which only shows up in sidebar, and other WebExtensions context menu items (for example "all", "page") won't be shown.

The "sidebar_action" context is supported in Opera, and the lack of support in Firefox prevents some Opera add-ons from working in Firefox.

(In reply to Tim Nguyen :ntim from comment #1) > The "sidebar_action" context is supported in Opera, and the lack of support > in Firefox prevents some Opera add-ons from working in Firefox. What does it actually do? browser/page_action menus are context menus on the button, not in the content of the panel. In Firefox ui, that makes no sense for the sidebar. If Opera supports a context menu of the sidebar button, then it wouldn't be the same as supporting sidebar *content* specific menus. I couldn't figure it out from their docs.

(In reply to Kazumasa Hasegawa (Kazz) from comment #0) > As I described in bug 1367160#c7 the contextMenus API can not be used in the > sidebar. > Clicking the menuitem will cause a TypeError. I have not been able to reproduce that in a simple test.

(In reply to Shane Caraveo (:mixedpuppy) from comment #2) > (In reply to Tim Nguyen :ntim from comment #1) > > The "sidebar_action" context is supported in Opera, and the lack of support > > in Firefox prevents some Opera add-ons from working in Firefox. > > What does it actually do? browser/page_action menus are context menus on > the button, not in the content of the panel. In Firefox ui, that makes no > sense for the sidebar. If Opera supports a context menu of the sidebar > button, then it wouldn't be the same as supporting sidebar *content* > specific menus. I couldn't figure it out from their docs. I can't remember, sorry. It can be found in the documentation though: https://dev.opera.com/extensions/apis/ You might find the addon that uses sidebar_action menus in this list: https://addons.opera.com/fr/extensions/?tag=sidebar&order=popular

(In reply to Shane Caraveo (:mixedpuppy) from comment #5) > (In reply to Kazumasa Hasegawa (Kazz) from comment #0) > > > As I described in bug 1367160#c7 the contextMenus API can not be used in the > > sidebar. > > Clicking the menuitem will cause a TypeError. > > I have not been able to reproduce that in a simple test. I've tested myself, but I could not reproduce it neither.

(In reply to Tim Nguyen :ntim from comment #6) > (In reply to Shane Caraveo (:mixedpuppy) from comment #2) > > (In reply to Tim Nguyen :ntim from comment #1) > > > The "sidebar_action" context is supported in Opera, and the lack of support > > > in Firefox prevents some Opera add-ons from working in Firefox. > > > > What does it actually do? ... > > I can't remember, sorry. Ok, sidebar_action works just like browser/page_action, placing a context menu on the button and not creating a context for the sidebar panel itself. Since our UI is different, this doesn't actually make sense for Firefox. The patch here allows an extension to specify a menu that appears in the context menu on the sidebar. I wonder whether we really care about that. I guess it may be useful for tab managers.

I think a context menu specific to the sidebar content area would be useful. As you said, alternate tab managers are probably the most likely candidate (vertical, tree-style) but I suspect there are others (e.g. alternate bookmark manager, notes, to-do lists, etc.).

Bulk move of bugs per https://bugzilla.mozilla.org/show_bug.cgi?id=1483958

- Support viewTypes property in menus.create / menus.update. - Add info.viewType to menus.onShown / menus.onClicked event. - This "viewType" reuses the existing extension.ViewType enum, which is a "tab", "popup" (pageAction/browserAction) or "sidebar".

This bug is mixing three distinct issues. Two of them ae no longer relevant, and the remaining one is handled by bug 1416839. (In reply to Kazumasa Hasegawa (Kazz) from comment #0) > As I described in bug 1367160#c7 the contextMenus API can not be used in the > sidebar. > Clicking the menuitem will cause a TypeError. (and comment 5, comment 7) This was bug 1409433, and already fixed. > I think "sidebar" context is needed, just like "tab" which only shows up in > sidebar, and other WebExtensions context menu items (for example "all", > "page") won't be shown. (and comment 8, comment 9) Extension menu items do already appear on sidebars. Bug 1416839 will allow extensions to show (or hide) menu items on sidebars only. (In reply to Shane Caraveo (:mixedpuppy) from comment #8) > (In reply to Tim Nguyen :ntim from comment #6) > > (In reply to Shane Caraveo (:mixedpuppy) from comment #2) > > > (In reply to Tim Nguyen :ntim from comment #1) > > > > The "sidebar_action" context is supported in Opera, and the lack of support > > > > in Firefox prevents some Opera add-ons from working in Firefox. > > > > > > What does it actually do? ... > > > > I can't remember, sorry. > > Ok, sidebar_action works just like browser/page_action, placing a context > menu on the button and not creating a context for the sidebar panel itself. > Since our UI is different, this doesn't actually make sense for Firefox. There are only three Opera extensions (last updated in 2026; unmaintained) that use sidebar_action and sidebar_action in the contextMenus API: - https://addons.opera.com/en/extensions/details/site-settings-sidebar/ - https://addons.opera.com/en/extensions/details/v7-extension-manager/ - https://addons.opera.com/en/extensions/details/v7-notes/ The API adds a menu item to the sidebar button, and as comment 8 concludes, we won't support custom menu items in the sidebar button menu.