Changes in Thunderbird 88
typeproperty to ComposeDetails, to distinguish between
fromproperty to ComposeDetails, to get/set the actual from address (independent of the used identity)
fixed quickSearch([parentId], queryInfo) to not fail on mailing lists
added listAttachments(messageId) and getAttachmentFile(messageId, partName) methods to work with message attachments
fixed getRaw(messageId) to work for nntp/news messages
Bugzilla list of fixed WebExtension API defects in Thunderbird 88.