From SeaMonkey Project's announcement:
SeaMonkey 2.29 contains the following major changes relative to SeaMonkey 2.26:
URLs that are too long to be shown completely appear in a tooltip now when hovering the location bar.
Coloring of the location bar for HTTPS URLs can be disabled through Preferences now.
Certain search engines can be discovered automatically now.
The status bar padlock icon features a context menu now.
You can now insert formulas in Composer using a dialog (LaTeX to MathML).
Feed items can be tagged automatically according to feed category tags now.
Searching within a message compose window will now display the find toolbar.
The account name is now shown in the status bar when downloading messages from POP servers.
Localizability of custom reply headers has been improved (mailnews.reply_header_* preferences).
Contact autocompletion in message composition windows now searches for all terms separately (AND search).
You can now search for contacts containing parentheses.
See the changes page for a more complete overview.
Mozilla platform changes
HTTP caching (v2) has been enabled.
Generational garbage collection has been integrated.
Public key pinning support has been enabled.
The number of found items is now displayed in the find toolbar.
The trust bit for some 1024-bit root certificates has been removed / turned off.
Support for the Prefer:Safe HTTP header for parental control has been added.
mozilla::pkix has been added as default certificate verifier.
The CAPS infrastructure for specifying site-specific permissions (via capability.policy.* preferences) has been removed.
WebVTT has been implemented.
CSS3 variables have been implemented.
CSP 1.1 nonce-source and hash-source have been enabled.
With the exception of those bundled inside an extension or ones that are whitelisted, plugins are no longer activated by default.
Added support for GStreamer 1.0 (see bug 806917 for build configuration).
Disabled insecure NTLM (pre-NTLMv2) authentication (see bug 828183).
Passwords can now be saved via the password manager even when autocomplete=off" was used to prevent it (see bug 956906).
Also see Firefox 32 for Developers, Firefox 31 for Developers and Firefox 30 for Developers.
Fixed several stability issues.
SeaMonkey 2.29 is available for Mac OS X, Windows and Linux. SeaMonkey 2.29 can be downloaded from this SeaMonkey 2.29 download webpage. Release notes is available as well.
UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:32.0) Gecko/20100101 Firefox/32.0 AlexaToolbar/alxf-2.21