Based on the mozilla-5.0 branch.
SeaMonkey 2.2 contains the following major changes relative to SeaMonkey 2.1:
Windows: Bundled extensions/add-ons are no longer optional in SeaMonkey's
installer.
Archive options can now be changed from the Copies & Folders Account Settings pane.
Mozilla platform changes
CSS Animations are now supported.
Improved canvas, JavaScript, memory, and networking performance.
Improved standards support for HTML5, XHR, MathML, SMIL, and canvas.
Improved spell checking for some locales.
WebGL content can no longer load cross-domain textures.
Background tabs have setTimeout and setInterval clamped to 1000ms to improve
performance.
MFSA 2011-10 CSRF risk with plugins and 307 redirects
MFSA 2011-08 ParanoidFragmentSink allows javascript: URLs in chrome documents
MFSA 2011-07 Memory corruption during text run construction (Windows)
MFSA 2011-06 Use-after-free error using Web Workers
MFSA 2011-05 Buffer overflow in JavaScript atom map
MFSA 2011-04 Buffer overflow in JavaScript upvarMap
MFSA 2011-03 Use-after-free error in JSON.stringify
MFSA 2011-02 Recursive eval call causes confirm dialogs to evaluate to true
MFSA 2011-01 Miscellaneous memory safety hazards (rv:1.9.2.14/ 1.9.1.17)
MFSA 2010-84 XSS hazard in multiple character encodings
MFSA 2010-83 Location bar SSL spoofing using network error page
MFSA 2010-82 Incomplete fix for CVE-2010-0179
MFSA 2010-81 Integer overflow vulnerability in NewIdArray
MFSA 2010-80 Use-after-free error with nsDOMAttribute MutationObserver
MFSA 2010-79 Java security bypass from LiveConnect loaded via data: URL meta
refresh
MFSA 2010-78 Add support for OTS font sanitizer
MFSA 2010-77 Crash and remote code execution using HTML tags inside a XUL tree
MFSA 2010-76 Chrome privilege escalation with window.open and <isindex> element
MFSA 2010-75 Buffer overflow while line breaking after document.write with
long string
MFSA 2010-74 Miscellaneous memory safety hazards (rv:1.9.2.13/ 1.9.1.16)
Also:
Fixes for a number of non-security-relevant crashes, increasing the
stability of the whole platform and the Mail & Newsgroups part of SeaMonkey
* Message-ID searches on Google Groups work again
* Add-ons preferences button for Lightning should work now
* Security fixes:
MFSA 2010-63 Information leak via XMLHttpRequest statusText
MFSA 2010-62 Copy-and-paste or drag-and-drop into designMode document allows XSS
MFSA 2010-61 UTF-7 XSS by overriding document charset using <object> type
attribute
MFSA 2010-60 XSS using SJOW scripted function
MFSA 2010-58 Crash on Mac using fuzzed font in data: URL
MFSA 2010-57 Crash and remote code execution in normalizeDocument
MFSA 2010-56 Dangling pointer vulnerability in nsTreeContentView
MFSA 2010-55 XUL tree removal crash and remote code execution
MFSA 2010-54 Dangling pointer vulnerability in nsTreeSelection
MFSA 2010-53 Heap buffer overflow in nsTextFrameUtils::TransformText
MFSA 2010-52 Windows XP DLL loading vulnerability
MFSA 2010-51 Dangling pointer vulnerability using DOM plugin array
MFSA 2010-50 Frameset integer overflow vulnerability
MFSA 2010-49 Miscellaneous memory safety hazards (rv:1.9.2.9/ 1.9.1.12)
MFSA 2010-33 User tracking across sites using Math.random()
MFSA 2010-32 Content-Disposition: attachment ignored
if Content-Type: multipart also present
MFSA 2010-31 focus() behavior can be used to inject or steal keystrokes
MFSA 2010-30 Integer Overflow in XSLT Node Sorting
MFSA 2010-29 Heap buffer overflow in nsGenericDOMDataNode::SetTextInternal
MFSA 2010-28 Freed object reuse across plugin instances
MFSA 2010-27 Use-after-free error in nsCycleCollector::MarkRoots()
MFSA 2010-26 Crashes with evidence of memory corruption
MFSA 2010-25 Re-use of freed object due to scope confusion
(missed those and *emacs* the first time round because they pull
in their png dependencies via default-on options; they were included
in the test bulk build though)
* Security fixes (MFSA 2010-16 through MFSA 2010-24)
* Fixes for a number of non-security-relevant crashes, increasing the
stability of the whole platform and the Mail & Newsgroups part of SeaMonkey
* ChatZilla localization packs work again (Bug 540842)
* FTP file upload was fixed (Bug 467524)
* The internal help content was updated some more
