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These versions are displayed for reference and testing purposes. You should always use the latest version of an add-on.
Moved browser/skin/devtools to devtools/skin
Fixed issue in Tools/Options
Bug 1263873 - Textbox for Tag prefix in Account Settings | Blog & News Feeds too small in localized Thunderbird and SeaMonkey
Bug 1268520 - Composition / general pref panel cut off if the font dropdown box is very wide
Bug 1263207 - Unable to add line breaks in email reply with quoted text with line-height:0
Bug 1308769 - Make the Edit Category dialog in-content capable
Bug 1260012 - Make it possible to hide the todayPane button text (always hide that text)
Many other little fixes & improvements
Fix tab icon for options tabpage
Fix toolbar badge margins
Fixed menubar issue (not selectable by mouse when autohide is turned on)
Bug 1247225 - False icon used for filelink notification bar in message compose window
Various little fixes and improvements.
Removed max-width on addons manager.
(Note, next version will increase minVersion to 38.0, so update your Thunderbird if it is older than 38.0)
Bug 866635 - refresh layout in the SMTP manager pane in the Account manager
Bug 364133 - Add Print option on context menu for individual address book contacts
Bug 1215905 - Get rid of the function updateStyle() in the New Event/Task dialog
Bug 1229141 - Use new itip icons in event summary dialog
Bug 1174511 - Show Required / Optional attendance on meeting invites received from other users
Improved main window styling
Improved design for addons manager / incontent preferences
And lots of other minor improvements and fixes.
Improved sort/filter in extensions
Bug 357012 - Week number support in multiweek/month view
Bug 368920 - Darken the background for Message Grouping (Group by Sort) headers
Fixed timezone selection window (and made it fully resizable)
Fixed MacOsX styling
Some minor style fixes.
Refined calendar view
Fixed drag markers for editable events
Fixed couple of issues with PrintingTools
Fixed MacOS window frame issues
Added full theming support for Compose Toolbar Buttons extension
Added support for Nostalgy extension
Bug 1146331 - In-content Preferences - Don't allow text selection of titlebars of subdialogs
Add smileys in chat.
Fix category coloring in calendar views.
Fix labelalign end for delete toolbarbutton.
Fixed cropping of subject/sender in mailheader
Fixed missing icon in addons manager
New layout for incontent options
Bug 1151474 - Remove use of expression closures in im/ .
Bug 1092526 - about:downloads needs CSS styles on each platform.
Bug 1003196 - Add icons to more imip bar buttons.
Bug 990009 - Rework imipbar buttons to offer more options to the user.
Bug 36489 Combined To/From column in thread pane.
And many other little fixes and improvements.
Improved calendar printing
Fixed header for browser popup for login
Fixed Twitter feed page
New addressbook icons
Bug 925746 - Option to Open the Preferences in a Tab
Bug 170270 - Enable search in multiple/all address books
Groupbox styling for walnut/2
Add-ons manager & incontent options: better position of the logo
Fixed spacing in Tools/Options/Applications
Bug 942638 - Clean up the multi-message summary code
Fixed privacy button icon in Options/Preferences
Fix appmenu button in other panels than the primary (calendar/chat/message)
Fixed tab height in maximized screen
Full support for ReminderFox
Restricted width of menulist in toolbars (prevent too wide fontselector in messengercomposer)
Optimizied icons for Addons Manager
Optimized alert/error/notification icons (saved 12KB)
Improved styling for toolbarbuttons/buttons/radio/checkmark/devtoolsbuttons
Improved styling for PluginProblem
Bug 318955 - Add optional Print button for message composition (customize composition toolbar)
Bug 362933 - Event dialog: Customize Toolbar dialog should offer more buttons for functionality
Bug 562048 - notification bar needs to look slicker
Bug 61491 - Autocomplete newsgroup names
Bug 397939 - [Today Pane] Allow more ways to navigate between the days
Bug 886124 - Add UI for extraction
Bug 939031 - Unable to drag window by empty space in tab bar.
Messengercompose: Move "to:" field close button to the end. Improved person icon
Messengercompose: improve layout of addressingwidget.
Move the audio volume bar in audio/video within the controlbar itself.
Use consistently same fonts for monospace and add Menlo for Mac.
Bug 920677 - Click-to-play plugins fail to show placeholder after resizing
Fixed fullscreen for html video
More consistent focus bar throughout (outline->box-shadow)
AccountCentral: added support for Create Account "submenu".
Added support for "Forward" extension.
Optimized addons list in addons manager and added wide display for wide screens.
Optmized/cleaner look for multimessageview.
Improved style for colorwell buttons.
Improved icon for Dictionaries button in addons manager.
Fixed event line in chat/twitter list.
Bug 877520 - Thunderbird should make use of exif orientation when displaying attached images
Added support for Mail Redirect
Added support for Google Task Sync
Improved styling for minimonth widget
Lots of minor fixes and improvements
Metal: extend background image size
Fix boldfacing of busy days in minimonth widget.
Fix appmenu and menu icons in messagewindow.
Display Contact Photo extension: Improved layout for contact photo's in message header and chat pages.
newmailalert: improved layout and nicer icon.
messagebody: correctly set spacing.
multimessageview: use messagedisplay font for the messages.
messageview: improved layout of header
Consistant image for buddy picture across messaging and chat.
Improved layout for invitations in message display and print.
Improved layout for task display.
Extensions: Removed old stuff from extensions.css
Extensions: color icon on mouse hover of addons
Improved spring icon
Overrule Linux images-in-button setting to always show button icons
Fixed tooltip margin
And a couple of minor improvements.
Styling of multimessage view made same as chat pane.
Couple of improvements of message display.
Cleaner styling for printing of messages/invites (easier for the printer)
Improved styling for addressbook
Added support for ReminderFox
Many other little fixes and improvements.
Some fixes for RTL.
Fixed context menu on the tabs
Added icon for appmenu
Some more layout fixes for message view.
Couple of minor tweaks
A couple of icons in the AppMenu.
Fixed margins on mail with specified background color
Bug 271730 - UI elements/widgets/controls in compose window should be disabled while the message is being sent (e.g. send button, options menu and attachments pane still wrongly enabled)
Improved FolderSummaries and AccountSummaries (MailSummaries extension)
Improved html viewer
Added support for ZombieKeys
Bug 735717 - chat - toolbar icon and tab icon are different
Improved console row layout.
Dirlisting: underline items when they are not files nor folder (ie when they are links)
Fixed table header alignment in PageInfo dialog
About pages: give first H1 header an information icon
statusbar/bottombox/addonbar improved styling
Information icon on header (first h1) of about: pages
Fixed icon for retry button in html pages (in most cases)
Improved mime attachments view in messageBody (and print)
Improved filter dialog layout
Optimized message header buttons
Fixed retry button icon in neterror.
Fixed typo in videocontrols.css.
Simplified and improved alerts.css
More icons for HTML buttons.
More subtle focus ring
Lightning tabmail button icons for Seamonkey.
Vcard display in sent email improved.
Fixed sizing of picture in addressbook.
Fixed menubar spacer insert issues during Customize Toolbar.
Removed toolbar button spacing change during Customize Toolbar.
Fixed transparency issues in Windows Aero.
Bug 314806 - Add ability to set default identity in the identity list editor (Account manager)
Bug 596234 - Body of RSS feeds won't print or print preview
Bug 757902 - Weekly and Monthly print layouts don't work, remove e4x usage (cpg fallout) (Print preview in Calendar)
Bug 650170 - Firefox-like Application Button/Menu for Thunderbird.
Bug 767327 - Add box.com to file link services
Improved print layout (mailheader/attachmentlist)
Fixed printing of RSS feed items
Fixed double borders in tools/options.
Fixed styling of links in Filelink panels/dialogs
Fixed print preview toolbar
Fixed window toolbar drag issue
MessengerComposer: more icons in menu's
MessageBody: better formatting of inline attachments.
Added support for the chromeless main window (Windows only)
messageBody: keep background color on message if it is set by the html mail.
Added support for SanitizeDialog.
Bug 741336 - Provide UI to easily clear cookies from the menus
Bug 767327 - Add (disabled) Box support for Filelink.
Bug 681735 - Make vertical space between actions in the Account central flexible
Bug 763522 - Show presence information in email headers,
Bug 748358 - Change the appearance of the chat button instead of reopening the chat tab when receiving a message.
Lots of image reduction (reducing the jar file with 143 KBytes)
Fixed timeIndicator bar in lightning calendar views
Improved style for invitation message display.
Flatter look for icons in message header.
Fixed invite dialog spacing & caption style
Bug 769095. Enforce maximum icon size for nsIAlertsService's notification.
Cleanup of disabled icons.
Cleanup of mozapps/reporter
Cleanup of old files in communicator
Bug 760625 - Use the blocklist to inform click-to-play plugins
Bug 761174 - Always show a property tooltip
Many other little styling & performance improvements.
Removed video throbber, saving 30K.
Fixed accountProvisioner dialog
Added support for Address Close Button extension.
Added support for Display Contact Photo extension.
Added support for MailSummaries extension.
Added support for ContactTabs extension.
Fixed ReplyToSender button
Added icon for UbuntuOne BigFile support
Improved chat buddy hover panel
Added icons for chat toolbar buttons.
Fixed issue with smileys in messengecomposer.
Make active button really depressed
Fixed more toolbarbuttons to support small icon mode.
Optimized video buttons and throbber, saving 30K.
Fixed collapse button in aboutCertError.css
More icons for about:permissions page
Use a patterned background for standalone/toplevel image view
Bold for non-zero elements in inspector/box view panel
Refined styling for file listing view
Optimized button in toolbar rules a bit
Bug 731041 - Tidy up addon inline preferences code, add labels for checkboxes, remove ugly description hack
Enabled small toolbar icons
Improved layout for BigFile options panels (dropbox/sendit)
Removed local.css (no longer needed). Removed xulbinding from smileys.
Lots of smaller style fixes and improvements.
Fixed missing icons for lightning in microthunderbird.
Fixed missing date chart in glodasearch view pane.
Bug 719008 - Add toolbar to Gloda search results tab with text input for modifying search query
Fixed About dialog for Earlybird.
Dropped support for Thunderbird 3.x, to be able to support TB 13 and higher.
Changed theme packaging to new style (no more nested jars).
Fixed double checkbox in 'Subscribe' dialog.
Added support for the new 'Chat' and 'FileLink' functions.
Bug 719008 - Add toolbar to Gloda search results tab with text input for modifying search query.
Bug 730483 - Remove dropped prefixes from comm-central
Bug 714733 - Instant messaging in Thunderbird
Bug 716706 - Fix and enhance the feed Subscriptions dialog
Bug 235666 - Next and Previous buttons should work on read messages
Bug 736155 - Outgoing attachments management pane seems squeezed on OSX and Windows (my fix is better than the default theme
as it doesn't rely of fixed widths)
Bug 715735 - Detail view icon has no dimensions set, causes a relayout when it loads
Bug 713822 - Simplify @media queries
Customize Toolbar palette: improved styling for separator, spring and spacer.
Bug 419231 - Floating scrollbar in the toolbar customization palette is funky.
Buttons, menulists, checkmark, radio: added drop shadow on hover.
Improved styling of addressingwidget in messengercomposer.
Made headerbar of addons manager same height and style as toolbars in other tabs.
Icons for toolbarbuttons in tabsobtop for Events & Tasks.
Fixed person icons in event-invite attendees dialog.
Improved styling of toprow buttons (zoom/prev/next) in Invite Attendees dialog
Bug 684518 - Task view rows get a border after restarting (aero theme not applied).
Bug 714390 - Folder Location and Mail Views items are cut off in the customize toolbar dialog
Re-enabled folder pane selector.
Optimized inclusion of global a bit.
Improved borders of message pane.
Fixed View selector in Calendar pane.
Added styling for attachment sizes in messengercomposer.
Bug 686420 - Cancelled events are not shown as cancelled in "Events and Tasks" bar (Today pane).
Bug 273279 - no visual status mark on tentative or cancelled events/tasks.
Many other little fixes and improvements