Manage your installed personas (lightweight themes).
Right Links Requires Restart
This extension allows to open links in new tabs with right-click directly and using “long” left-click.
This is very useful for touchpads on notebooks and for mice without middle button.
Adds icons to buttons and/or menus.
Restores the default image style used for top-level images in previous versions of Firefox.
The Add-ons Manager slims down!
This add-on reduces the height of entries in the Add-on Manager, so you can display more of them at a time.
Speed Dial & Start Page with flexible layout for fast access to sites via visual bookmarks
FolderFlags Requires Restart
Allows users to edit the flags Thunderbird sets on folders.
Duplicate This Tab Requires Restart
This add-on provides the much needed feature update of Tab Duplication to Mozilla Browsers. Features Supported include Duplication of Browser Tabs, Detaching Tabs and Merging All Windows.
Compact Menu 2 Requires Restart
Add a compact menu button to the navigation toolbar, and hide the menu bar.
YouTube Video Player Pop Out lets you pop out YouTube videos so that you can watch YouTube videos while you surf.
See more search results etc. on one page, concatenating several pages together...
This extension enables true full screen mode in SeaMonkey for HTML5 video players, slide-shows, etc. and also for full screen invoked manually with the F11 key.
IMAP Received Date Requires Restart
Make the “Received” column in IMAP folders show when messages were actually received.
HTitle (discontinued) Requires Restart
Hide title bar if window is maximized.
This add-on has been discontinued!
Legacy extensions support will be dropped in Firefox 57. If you interest in CSD on Linux, please track progress on https://bugzilla.mozilla.org/show_bug.cgi?id=1283299.
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.
Active Stop Button Requires Restart
Stop gif animation with button, context menu or Esc key
Key config Requires Restart
This add-on provides configurable keyboard shortcuts for several actions and a dialog to customize them.
All shortcuts can be redefined in Tools -> Key settings
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
Sync engine for Stylish with backup / restore facility.
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