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

Thunderbird, Postbox

Print Preview

Open Print Preview

Open the Print Preview to view a page before printing it.

Paper costs money (and trees) so it is worth checking what the page looks like before you print it. Though it has always amazed me just how much the button gets downloaded.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

About

About

Open the about window. Useful for checking exactly what version you have installed.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

about:plugins

Open about:plugins to view installed plugins

Open about:plugins to view installed plug-ins.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Copy

Copy Selected Text

Copy selected text.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Find

Find Text

Open the find bar to find a word in the current page.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Free Memory

Free Unused Memory

Free unused memory that Firefox is currently using.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Hide Toolbars

Toggle visibility of all toolbars, except the main toolbar

Toggle the visibility of all toolbar, other then the main toolbar.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Passwords

Open Password Manager

Opens the password manager to view saved passwords

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

Add-on Preferences

Open the preference window of an add-on.

Displays a submenu that allows you to open the option window for any add-on that has one.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey