Thunderbird 5 folder pane and Mac OS X 10.7 (aka Lion)

Due to the new window resizing feauture of Lion, there is as strong possibility that one can’t get the folder pane back in Thunderbird if it snaps shut (because you will resize the window, not reopen the pane at the left border). One can re-enable it by editing the file in session.json in the profile directory (~/Library/Thunderbird/Profiles/*.default/session.json) and replacing “folderPaneVisible”:false with “folderPaneVisible”:true. This should probably be done with Thunderbird closed. Upon reopen, the folder pane should be back.

Hopefully this will be fixed in the next Thunderbird version…