What is No Message Pane Sorting by Mouse?
Do you accidentally resort your messages in Mozilla Thunderbird because your mouse click hits the message pane header instead of the top most message?
Then No Message Pane Sorting By Mouse is the addon you've been waiting for. It disables mouse buttons clicks on the message pane headers and your message list stays sorted all the time.
Resorting via the View -> Sort by menu still works -- just in case you do need to resort your messages.