Changes in Thunderbird 78.6.0

browserAction

• The setLabel(details) and getLabel(details) functions have been added. It is now possible to set a label value different from the title (which is used as tooltip text). The label can be set to an empty string to make the action button not have a label at all. If the toolbar is set to text-mode only (no icons), the action button label uses the title as fallback, in case an empty label has been set.

composeAction

• The setLabel(details) and getLabel(details) functions have been added. It is now possible to set a label value different from the title (which is used as tooltip text). The label can be set to an empty string to make the action button not have a label at all. If the toolbar is set to text-mode only (no icons), the action button label uses the title as fallback, in case an empty label has been set.

menus

• The standard properties available to onShown are now available for messages being composed, if your extension has the compose permission.

messageDisplayAction

• The setLabel(details) and getLabel(details) functions have been added. It is now possible to set a label value different from the title (which is used as tooltip text). The label can be set to an empty string to make the action button not have a label at all. If the toolbar is set to text-mode only (no icons), the action button label uses the title as fallback, in case an empty label has been set.

windows

• The openDefaultBrowser(url) function has been added.