Changes in Thunderbird 111
Improved open(openProperties) to honour the
locationproperty also for external messages. They can now also be opened in tabs.
Fix Thunderbird to properly support the protocol_handlers API.
Fix create([createData]) to properly support
beforeunloadevent not fired in popup windows. Note: There must have been some sort of interaction with the window (for example a mouse click into the window), for this event to be fired when the window is closed.