Applies when the user context-clicks your browser action in a Manifest V3 extension. The maximum number of items that can be added to the top-level browser action context menu is menus.ACTION_MENU_TOP_LEVEL_LIMIT, but you can add any number of items to submenus.
Applies when the user context-clicks a bookmark item in the bookmarks toolbar, bookmarks menu, bookmarks sidebar (Ctrl+B) and the Library window (Ctrl+Shift+B). The latter two are supported as of Firefox 66. Requires the "bookmarks" API permission in the manifest.
Applies when the user context-clicks your browser action in a Manifest V2 extension. The maximum number of items that can be added to the top-level browser action context menu is menus.ACTION_MENU_TOP_LEVEL_LIMIT, but you can add any number of items to submenus.
Applies when the user context-clicks in the page, but none of the other page contexts apply (for example, the click is not on an image or a nested iframe or a link).
Applies when the user context-clicks your page action. The maximum number of items that can be added to the top-level page action context menu is menus.ACTION_MENU_TOP_LEVEL_LIMIT, but you can add any number of items to submenus.
Applies when the user context-clicks on a tab (specifically, this refers to the tab-strip or other user interface element enabling the user to switch from one browser tab to another, not to the page itself).
From Firefox 63, clicking the menu item on a tab grants the activeTab permission for the tab clicked, even if that isn't the currently active tab.
The item will be added to the browser's tools menu. Note that this is only available if you access ContextType through the menus namespace. It is not available if you access it through the contextMenus namespace.