Font Finder Requires Restart
FontFinder is created for designers, developers and typographers. It allows a user to analyze the font information of any element on a page, copy any piece(s) of that information to the clipboard, and perform inline replacements to test new layouts.
'Classic Toolbar Buttons' add-on restores old toolbar button ui (known from Fx 4-7s small view, Fx 4-12s large view & Tb 5-14) for current Firefox, Thunderbird and Seamonkey versions.
Beta builds on versions page!
Google Keep for Thunderbird
UnMHT allows you to view MHT (MHTML) web archive format files, and save complete web pages, including text and graphics, into a single MHT file in Firefox/SeaMonkey.
Ad Blocker lets you block all ads, tracking & malware from the web world. It is an effective solution to browse the web without offensive and annoying ads you hate to see.
A powerful ad blocker that blocks ALL ads but ads from publishers who shares revenues with targets YOU choose.
Add Signature Requires Restart
Simply add your signature manually (right mouse click) to your emails
Fight the text ads! Element Hiding Helper is a companion extension for Adblock Plus meant to make creating element hiding rules easier.
Deselect on Click 1.0 Requires Restart
Deselects current message when clicking in thread pane.
Force Addon Status Requires Restart
Provides ability to change status of specific addon (enabled/disabled).
Nightly Tester Tools Requires Restart
Useful tools for the nightly tester.
DOM Inspector Plus! [dm] Requires Restart
Improved DOM Inspector! [dm version]. Box Model new layout & more data, see screenshot!. Horizontal scroll for Dom-Tree, and some more.
Inspects the structure and properties of a window and its contents.
NewScrollbars (aka NoiaScrollbars) Requires Restart
The "NewScrollbars"-extension replaces default scrollbars of Firefox and Thunderbird with colorized ones (partly) known from "Noia themes".
Auto Compress File Requires Restart
Compressor for attachment files. All platforms are supported (Windows, Linux and Macintosh).
PathExplorer Requires Restart
Adds "Open with Explorer" to the message pane's right-click menu.
Auto Resize Image Requires Restart
Resizer for inline and attachment images (JPEG, PNG, BMP and GIF image formats).
All platforms are supported (Windows, Linux and Macintosh).
LightningButton Requires Restart
Toolbar-Buttons for Lightning; advances the feature to get rid of the tabbar.
Subject Manager Requires Restart
Manages subject of composed emails.
If you are the kind of person who likes to have total control over every aspect of your downloads, "Download Status Bar" is the add-on you are looking for.