ThreadKey Requires Restart
Strike the 'T' key to sort messages by thread, strike the 'U' key to sort them unthreaded again, just like the 'G' key switches to Grouped By Sort view.
MinimizeToTray Reanimated Requires Restart
MinimizeToTray Reanimated is an application mainly dedicated to Thunderbird to allow its minimization in the systray in one click. It is the update of MinimizeToTray Revived, which is not maintained anymore since the recent versions of Thunderbird.
Speed Dial & Start Page with flexible layout for fast access to sites via visual bookmarks
Menu Wizard Requires Restart
Customize menus : Helps removing, moving and renaming menus and menu items
Colorize important menu for ease of use! (use Style (CSS))
Change or disable any of used keyboard shortcuts
Support: Firefox, Thunderbird and SeaMonkey
'Classic Toolbar Buttons' add-on restores old toolbar button ui (known from Fx 4-7 small view, Fx4-12 large view & Tb5-14) for current Firefox, Thunderbird and Seamonkey versions.
Add-on for Thunderbird that replaces the built-in notifications with OS native ones. It supports most Linux Desktop Environments as well as Windows 8.1/10.
Tategaki Requires Restart
Tategaki allows vertical writing-mode on mail compose window.
Sort and Search Customization Dialogs Requires Restart
Sort and search for buttons in (any) toolbar customization dialog
Dorando keyconfig Requires Restart
A modified Dorando's addon to rebind keyboard shortcuts. It is designed to be a drop-in replacement, keeping your old settings. (See details for upgrade instructions.)
Theme Font & Size Changer lets you change the global font size and font family used for the user interface in Firefox. Design your browser with your favorite font.
This extension makes browsing for extensions easier at addons.mozilla.org. It fixes incorrect information about some extensions being not available for SeaMonkey and adds links to the Add-on Converter where needed.
Adds icons to buttons and/or menus.
GNOMErunner Options Requires Restart
Allows to customize GNOMErunner theme
Makes every page to have light text on dark background (exact colors are customizable)
Firefox version is here: https://addons.mozilla.org/firefox/addon/dark-background-light-text/
Password Tags Requires Restart
Adds metadata and sortable tags to the password manager.
Simple Locale Switcher Requires Restart
An easier management of the user interface language
Restores version numbers for all installed add-ons inside Add-on Manager on Firefox, Thunderbird and Seamonkey.
Active Stop Button Requires Restart
Stop gif animation with button, context menu or Esc key
Stylish-Custom Requires Restart
custom additions to Stylish extension
FLST (Firefox 4+) Requires Restart
Provides Focus Last Selected Tab and Tab flipping functionality (based on the FLST extensions by Gorgias and Gozer, but ported to Firefox 4/.../56 and repaired Tab flipping functionality). Enjoy!