> For the complete documentation index, see [llms.txt](https://developer.thunderbird.net/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.thunderbird.net/add-ons/mailextensions/supported-ui-elements.md). # Supported UI Elements ## Browser Action A browser action adds a button to Thunderbird's main toolbar: ![](/files/-MJ90vnov5TcfO6CiXBg) It is controlled by the `browser_action` manifest key in the extension's `manifest.json` file: ```javascript "browser_action": { "default_title": "Restart", "default_icon" : "restart.png", "default_popup": "browser_popup.html" }, ``` If a `default_popup` is defined, a popup will be opened and the defined html page will be loaded, when the button is clicked. Additionally, you can use the [browserAction](https://webextension-api.thunderbird.net/en/mv2/browserAction.html) API in your background script to interact with the button to modify *badge text*, *icon*, *title* or its *enabled state*. If the action button is defined as a [menu typed action button](https://github.com/thunderbird/webext-examples/tree/master/manifest_v2/menuActionButton), it will open a drop-down menu when clicked. **Note:** The `browserAction` API has been renamed to `action` in [Manifest V3](https://webextension-api.thunderbird.net/en/mv3/action.html). ## Compose Action A compose action adds a button to the toolbar of the composer window: ![](/files/-MJ91Vy66ElvcV7dj-nO) It is controlled by `compose_action` manifest key in the extension's `manifest.json` file: ```javascript "compose_action": { "default_title": "Expand lists", "default_icon" : "lists.png", "default_popup": "compose_popup.html" }, ``` If a `default_popup` is defined, a popup will be opened and the defined html page will be loaded, when the button is clicked. Additionally, you can use the [composeAction](https://webextension-api.thunderbird.net/en/mv2/composeAction.html) API in your background script to interact with the button to modify *badge text*, *icon*, *title* or its *enabled state*. If the action button is defined as a [menu typed action button](https://github.com/thunderbird/webext-examples/tree/master/manifest_v2/menuActionButton), it will open a drop-down menu when clicked. ## Message Display Action A message display action adds a button to the toolbar of the message view window: ![](/files/-MLrqNTSKKn-E5wOXpIp) It is controlled by the `message_display_action` manifest key in the extension's `manifest.json` file: ```javascript "message_display_action": { "default_title": "Copy Patch", "default_icon" : "patch.png", "default_popup": "message_popup.html" }, ``` If a `default_popup` is defined, a popup will be opened and the defined html page will be loaded, when the button is clicked. Additionally, you can use the [messageDisplayAction](https://webextension-api.thunderbird.net/en/mv2/messageDisplayAction.html) API in your background script to interact with the button to modify *badge text*, *icon*, *title* or its *enabled state*. If the action button is defined as a [menu typed action button](https://github.com/thunderbird/webext-examples/tree/master/manifest_v2/menuActionButton), it will open a drop-down menu when clicked. ## CloudFile Provider Configuration Thunderbird supports cloud providers to upload large attachments to a server, instead of attaching them directly to the email. Extensions can register such cloud providers using the [CloudFile](https://webextension-api.thunderbird.net/en/mv2/cloudFile.html) API. These providers can be managed in Thunderbird's Composition options: ![](/files/-MM0CfQCHDEkLtJfXMen) ## Menu Items The [menus](https://webextension-api.thunderbird.net/en/mv2/menus.html) API allows modifying Thunderbird's menus by adding or overriding menu items. The menu items can be added to different menus based on the provided `context` type. Examples can be found in our [example repository](https://github.com/thunderbird/webext-examples/tree/master/manifest_v2/menu). Thunderbird menus are accessible through the following context types:
ContextDescription
allAdd menu entries to all supported contexts, excluding tab and tools_menu.
all_message_attachmentsAdd entries to the context menu of the summary area of message attachments.



If the message has only one attachment, then the message_attachments context is used instead.
action,
browser_action, compose_action , message_display_action

Note: browser_action is available in Manifest V2 and action is available in
Manifest V3.		Add entries to the context menu of action buttons.

action_menu,
browser_action_menu, compose_action_menu, message_display_action_menu,

Note: browser_action_menu is available in Manifest V2 and action_menu is available in Manifest V3.

Add entries to the drop-down menu of menu typed action buttons.

compose_attachmentsAdd entries to the context menu of attachments in the compose window.

editable,
password

Add entries to the context menu of text/password input fields in WebExtension windows, web tabs or message display tabs.

Limited to content areas.

folder_paneAdd entries to the context menu of the folder pane of mail tabs.

image,
audio,
video		Add entries to the context menu of embedded images, audio or video players in WebExtension windows, web tabs or message display tabs.

Limited to content areas.

link

Add entries to the context menu of links in WebExtension windows, in web tabs or in message display tabs.


Limited to content areas.

message_attachmentsAdd entries to the context menu of attachments of messages.

message_listAdd entries to the context menu of the message list area of a mail tab.

page,
frame

Add entries to the context menu of WebExtension windows, web tabs or message display tabs, if none of the other content contexts apply (link, selection, image, audio, video, editable, password).


If the page is loaded inside a frame, the frame context applies, otherwise the page context.

Limited to content areas.

selection

Add entries to the context menu in WebExtension windows, web tabs or message display tabs, if any text has been selected.

Limited to content areas.

tab

Add entries to the context menu of tab ribbons.

The tab context can also be used to override the context menu of content pages (action popups or content tabs).

See the menu example for more details.

tools_menuAdd entries to Thunderbird's tools menu.