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
Edit Bookmark Plus Requires Restart
Resize 'Add Bookmark' Popup / 'Edit This Bookmark' Popup, fixes tree selection bug, option to disable popup auto close & Update Url and/or Name of a bookmark with the Url/Title of current page.
Replacement of OpenBook addon
KeePass Helper Requires Restart
Adds a hostname, URL, or email account ID to the application's window name (e.g., that of Firefox or Thunderbird) to make it recognizable to password manager utilities like KeePass.
ImageTweak: zoom/rotate images and videos! Requires Restart
A no-clutter image viewer for Firefox that allows you to zoom, rotate and display images/videos against a custom background. ImageTweak is a must-have addon for any photographer or photography-loving user.
Restart Application Button lets you restart your Firefox and SeaMonkey application by a quick toolbar button click.
Compact Menu 2 Requires Restart
Add a compact menu button to the navigation toolbar, and hide the menu bar.
Adds buttons to toggle the using the default page colors and fonts, and the page defined colors and fonts.
Manage your installed personas (lightweight themes).
Tabs Menu Requires Restart
Adds a Tabs menu to the main menu that lets you easily change between tabs.
xSidebar Requires Restart Featured
Firefox style sidebars for SeaMonkey...
InspectorWidget Requires Restart
Adds toolbar button and context menus for invoking the DOM Inspector (DOMi) for either chrome or content elements.
SeaTab-X-2 Requires Restart
Adds Firefox-style tab closers into SeaMonkey.
Duplicate Tab Requires Restart
Duplicate Tab allows you to clone a tab along with its...
Tab Clicking Options Requires Restart
Select actions for various clicking events on a tab or the tab...
Stylish Tools Requires Restart
Quicker access to several Stylish features through a toolbar button and/or keyboard shortcuts. Available for Firefox, Thunderbird, and SeaMonkey
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.
Xclear Requires Restart
Safari-like icons in the URL, search and find fields to clear their contents.
HTML5 Loop Requires Restart
Loop HTML5 Video and Music.
SeaMonkey Vertical Tab Bar Requires Restart
Tab bar on the side of the window for SeaMonkey.
See more search results etc. on one page, concatenating several pages together...