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

Thunderbird, Postbox

Tasks In View

Toggle the Task in View panel in Sunbird.

Install Tasks In View

Download Tasks In View

Compatibility: Thunderbird, Postbox SeaMonkey

Threads with Unread

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

Install Threads with Unread

Download Threads with Unread

Compatibility: Thunderbird, Postbox SeaMonkey

Toggle Read

Toggle the Read status of the currently selected message.

Install Toggle Read

Download Toggle Read

Compatibility: Thunderbird, Postbox SeaMonkey

Toggle Starred

Toggle the starred status (look for the star next to the message).

Install Toggle Starred

Download Toggle Starred

Compatibility: Thunderbird, Postbox SeaMonkey

Toggle Tasks

Toggle the task bar between visible and hidden.

Install Toggle Tasks

Download Toggle Tasks

Compatibility: Thunderbird, Postbox SeaMonkey

Unread Threads

View threads that you have not read yet.

Install Unread Threads

Download Unread Threads

Compatibility: Thunderbird, Postbox SeaMonkey

Watched Threads with Unread

View watched threads that have unread messages in them.

Install Watched Threads with Unread

Download Watched Threads with Unread

Compatibility: Thunderbird, Postbox SeaMonkey