Changes in Thunderbird 89

mailTabs

• added getCurrent() and get(tabId) functions

menus

• fixed browser_action ContextType

• added message_display_action and compose_action ContextType

• introducing a fieldId property to OnClickData and OnShowData to to support fields part of the Thunderbird UI (currently supported values are composeSubject, composeTo, composeCc, composeBcc, composeReplyTo and composeNewsgroupTo)