SeaMonkey 2.49.4

- Implemented an option to thread messages received by date.
- Allowed deletion of news posts by default.
- Implemented optional taskbar preview-per-tab.
- Added support (permission prompt) for desktop notifications.
- Added Isn't operator for searching by Priority.

# Fixes
- The zoom in/out cursor did not appear when hovering images.

# Fixes
* Some private windows appeared in the undo close window list.
* The Private Browsing shortcut key has been changed as it conflicted with spellcheck.
* Remote debugging did not work if any tabs had no title.
* Clicking on new mail notifcation opened two MailNews windows when no MailNews window was open.

# Fixes
* On Mac OS X, all plugins are now run out of process by default when in 32-bit mode (i386/x86).
* The About SeaMonkey page claimed to be on the "default" update channel.

# Features
* The Content Security Policy (CSP) 1.0 parser has been enabled.
* The Mixed Content Blocker has been enabled, blocking insecure active content loads on HTTPS pages.
* New mail alert information can be customized now (Preferences/Mail & Newsgroups/Notifications).
* A confirmation prompt has been introduced to protect against accidental permanent data loss when force-deleting messages using Shift+Del.
* MailNews Save As Template supports multiple selections now.
* The size on disk is now shown for newsgroup folders.
# Fixes
* The Publish Webpage prompt in Composer has been fixed.
* Reporting a phishing site no longer sends potentially sensitive information from query parameters.
* POP3 local inbox folders no longer grow past the 4 GB limit when getting mail.
* MailNews search, filter and mail views no longer include messages on the date with "date" "is after"/"is before".
* Session restore now ensures restored windows are actually on-screen.
* The search bar no longer saves the search history in private windows.
* The SSL Preference pane has been updated to accommodate changed preference names and semantics.
* Crtl+clicking a link opens it now even if the click event handler calls event.stopPropagation().
* The Get Mail popup menu is now restored to full width after customizing the toolbar.
* MailNews folder size checks check the available disk space now.
* Attaching a message without trailing line break no longer corrupts the attachment.
* The browser feed preview has been adapted for Private Browsing.
* The MailNews subscribe dialog has been improved (the server of the selected folder is now selected and subscription checkboxes are now accessible).
* Balloon notifications on new mail are no longer shown if the tray icon is disabled.
* Compacting large mail folders should be more stable now.

# Fixes
* Selecting saved search folders in MailNews could lead to a crash.

# Fixes
- Mitigate clickjacking of about:certerror.
- Workaround for unusually large DirectWrite font line heights.
- Private downloads should ignore the Download Manager.
- Private windows should not opt out of the private browsing session.
- Private sidebar searches should not open in a normal window.
- Last page visited should not include private browsing windows.

# Features
* Mark -> As Read now checks the state of all selected messages instead of only the first one's.
* Notifications for mixed content blocker have been implemented.
* A new 3rd-party cookie restriction to visited websites option has been added to the Cookies pref pane.
* The context menu Search option is now available for textareas and input fields.
* Website storage mechanisms are now available in the Data Manager (localStorage, indexedDB, etc.).
* "Open Containing Folder" is now already available during download.
# Fixes
* The new mail alert has been disabled for now due to issues on Mac.
* The Geolocation prompt does not offer an action in Private Browsing mode anymore if the action remembers permission for more than a session.
* A slightly less useless access key has been chosen for the new Error Console Filter textbox label.
* Mixed content blocker preferences are now handled by Sync.
* LDAP passwords were requested for each lookup even if they were saved.
* Get New Messages for All Accounts has been fixed.
* The "File" button in the "Search messages" window has been renamed to "Move".
* The entries in the "Trust junk mail headers set by" menu list are now sorted.
* The check for the allowed mail storage directory has been made more universal and accessible to extensions.
* A wrong message and reason was reported with untrusted CA roots when signing email.
* The IMAP-specific "Empty trash" confirmation dialog has been removed and the mailnews.*.dontAskAgain and mail.*.dontAskAgain prefs been merged.
* Help now explains what happens when Safe Browsing blocks a website.
* Email addresses with trailing whitespace could be displayed wrongly when composing and cause lost mails and malformed duplicate address book entries.
* Switching the account during message composing did not apply the signing prefs from the new account.
* The Help Glossary has been extended with new Privacy & Security terms.
* Growl support has been removed again.
* Safe Browsing debug has been turned off and Sync support turned on.
* The Bookmarks Toolbar was not populated with items if the grippy was collapsed when the browser window was opened.
* Special mail folder icons were not shown for IMAP shared folders.
* Null bytes are now stripped from document titles when setting the window title in order to prevent Private Browsing spoofing.
* Invalid message ContentType values are handled better now.
* A tutorial section on User Tracking has been added to Help.
* The Customize Headers window prompted twice.
* ReplyTo has been added to the default IMAP headers in order to fix Reply with Template behavior.
* The offline folder flag will no longer be set for SPAM and TRASH folders.
* Help now includes documentation for the Offline Applications pref pane.
* The main Privacy & Security pref pane is now documented and features a Help button.
* The access key for "Perform these actions" now sets/moves focus to first action item in the Filter editor.
* Clear Private Data (preferences and menu) documentation has been added to Help.
* An "Error parsing template: expected <content> to be first" message could appear when opening the virtual folder list dialog.
* The umask for emails saved as a file were not respecting the system umask.

- Lightweight themes crunched the window title bar on Mac OS.
- The Print button was misaligned in the Composer and Message Composition toolbars with the Modern theme.