Rated 5 out of 5 stars

This module is essential as long as the shortcut is not natively integrated into Thunderbird! My users hate the threaded view, and deactivating it via the menu is a real pain.

The only thing missing from this extension is an icon, to be added to the icon bar, to switch from one mode to another without using the keyboard shortcut. But it works perfectly without it. Thanks al lot!

Glad to know it works for you.

I actually find the threaded view useful especially when following up multiple messages with long conversation. At the same time, it also has an inherent drawback when new messages arrive because they could be part of threads which are not currently visible which could lead to a situation where users (I experienced this) do not promptly respond to them.

To the extent I know the default shortcut Ctrl+T is not tied to any Thunderbird commands. But even if it is, users can always change it any valid shortcut.

As for the icon, that is doable; maybe someday.