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

Thunderbird, Postbox

about:config

Open about:config to change settings

Open about:config to change hidden settings that cannot be edited from the Options window.

All Mozilla based programs have settings that can not be changed in the options window. These hidden settings are all reveled in the about:config where anything can be changed or reset.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Add-ons

Open Add-ons Manager

Opens the Add-ons window to perform tasks on your installed Extensions, Themes, Plug-ins and Language packs.

The Add-on's window allows the installation and management of all your extensions and themes. If you need an update, change a setting, swap themes or enable/disable an add-on the Add-ons' window is the place to go. Being able to access this quickly is a necessity for anyone that uses even a handful of add-ons.

The button also contains a drop down menu that allows you to install add-ons, open the add-ons window to the extension or themes tab, or set which websites can install addons.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Restart

Restart Application

Restart the current application after installing a new extension, theme or plug-in.

There is a number of reasons you may want to restart the program your using. Though having installed an extension is the most common. This button take all the hassle and work out of it.

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

Undo

Undo Last Change

Undo last change/action.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Redo

Redo Last Change

Redo the late change.

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

Extensions

Open Extension Manager

Open the Extensions Manager to install, uninstall or do any other needed tasks to any of your extensions.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Save

Save document as

Save the currently open document, or image to a file.

Saving a page or email for later viewing or to send to a friend is a much needed functionality, so much so that there really should be a toolbar button for it.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey

Zoom Out

Reduce Text Size

Reduce the text size so it is not so big.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey