In short, Maximize Message Pane changes the layout of the message panes. If there are some bugs or conflicts with other extensions, the layout may be corrupted and could not be recovered. If you are in the situation, please delete localstore.rdf in your profile directory and restart Thunderbird. In spite of the recovery, if the problem is not solved, please feel free to ask me by email or posting to blog before giving up and recreate the profile.Maximize message pane by collapsing the thread pane. You can read a message in larger area without opening a new message window.Here are some key features of \"Maximize Message Pane\":