I had the same problem. I went into Advanced Desktop Settings > Window Management > Extra WM Actions and turned the "Toggle Fullscreen" option on, assinging it to Alt-F11. I then simply pushed Alt-F11 while Thunderbird was highlighted and everything was fine.
I had the same problem. I went into Advanced Desktop Settings > Window Management > Extra WM Actions and turned the "Toggle Fullscreen" option on, assinging it to Alt-F11. I then simply pushed Alt-F11 while Thunderbird was highlighted and everything was fine.