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

Thunderbird, Postbox

about:plugins

Open about:plugins to view installed plugins

Open about:plugins to view installed plug-ins.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Toolbar Display

Change Toolbar Icon Size and Display Mode

Set the toolbar icon size as either large or small, and the button display mode between icons, icons and text, or text only.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Toggle Proxy

Toggle The Proxy On & Off

Toggles the Proxy between on and off for quick changing of networks.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Zoom In

Enlarge Text Size

Enlarge the text size on sites that makes the text so small you can't read it.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Codefisher

Open Codefisher.org

Opens various pages of the Codefisher.org website.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Plugins

Open Plugin Manager

Open the Plugin Manager to enable or disable or do any other needed tasks to any of your plugins.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Run Application

Run an external application

Runs an external application

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Toggle menu bar

Toggle the menu bar

Toggle the menu bar. Don't put this button on the menu bar!

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Tools Menu

Show the tools menu

Show the tools menu.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Minimize

Minimize current window

Minimize the current window.

I hate popups that don't show the minimize button on the window itself. This has been my solution. Also when I use full screen mode, and then want to minimize the window, this again this comes in useful.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey