These are a ready make selection of some of the most popular buttons from the Custom Toolbar Button Maker

Thunderbird, Postbox

Rewrap

Rewrap

Rewraps the message text

Compatibility: Thunderbird, Postbox SeaMonkey

Tasks In View

Toggle Tasks in View

Toggle the Task in View panel in Sunbird.

Compatibility: Thunderbird, Postbox SeaMonkey

Themes

Open Themes Manager

Open the themes manager to change you theme or install a new one.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Threads with Unread

View Threads With Unread

View only the threads in the current folder that have unread messages.

Compatibility: Thunderbird, Postbox SeaMonkey

Toggle Tasks

Toggle the task bar

Toggle the task bar between visible and hidden.

Compatibility: Thunderbird, Postbox SeaMonkey

Tools Menu

Show the tools menu

Show the tools menu.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Unread Threads

View Unread Threads

View threads that you have not read yet.

Compatibility: Thunderbird, Postbox SeaMonkey