Changes in Thunderbird 113

action APIs

Removed the user input requirement from openPopup([options]), openPopup([options]) and openPopup([options]). Also added support for the windowId property, to open the popup of a specific window. Furthermore, openPopup() now returns a boolean value, indicating whether opening of the popup has failed, because the action button or the entire toolbar has been removed by the user.
Fixed the annoying issue on MacOS, where the popup was opened empty after the second time it was opened. A big shout out to Arnd Issler for helping to track this down.
Added allowed_spaces manifest entry, to let add-ons define in which space the action button should be allowed in.

Fix compose API to no longer clear all (!) headers, if setComposeDetails(tabId, details) is used to update the non-standard X- headers.

Add support for WebExtension defined protocols to be accepted as command line arguments. More details can be found in the bug.

Bugzilla list of all fixed WebExtension API bugs in Thunderbird 112 and Thunderbird 113.