What is different about Emacs 22?
Emacs can be built with GTK+ widgets, and supports drag-and-drop operation on X.
Emacs 22 features support for GNU/Linux systems on S390 and x86-64 machines, as well as support for the Mac OS X and Cygwin operating systems.
The native MS-Windows, and Mac OS X builds include full support for images, toolbar, and tooltips.
Font Lock mode, Auto Compression mode, and File Name Shadow Mode are enabled by default.
The maximum size of buffers is increased: on 32-bit machines, it is 256 MBytes for Emacs 23.1, and 512 MBytes for Emacs 23.2 and above.
Links can be followed with mouse-1, in addition to mouse-2.
Window fringes are customizable.
The mode line of the selected window is now highlighted.
The minibuffer prompt is displayed in a distinct face.
Abbrev definitions are read automatically at startup.
Grep mode is separate from Compilation mode and has many new options and commands specific to grep.
The original Emacs macro system has been replaced by the new Kmacro package, which provides many new commands and features and a simple interface that uses the function keys F3 and F4. Macros are stored in a macro ring, and can be debugged and edited interactively.
The Grand Unified Debugger (GUD) can be used with a full graphical user interface to GDB; this provides many features found in traditional development environments, making it easy to manipulate breakpoints, add watch points, display the call stack, etc. Breakpoints are visually indicated in the source buffer.
Many new modes and packages have been included in Emacs, such as Calc, TRAMP, URL, IDO, CUA, ERC, rcirc, Table, Image-Dired, SES, Ruler, Org, PGG, Flymake, Password, Printing, Reveal, wdired, t-mouse, longlines, savehist, Conf mode, Python mode, DNS mode, etc.
Leim is now part of Emacs. Unicode support has been much improved, and the following input methods have been added: belarusian, bulgarian-bds, bulgarian-phonetic, chinese-sisheng, croatian, dutch, georgian, latin-alt-postfix, latin-postfix, latin-prefix, latvian-keyboard, lithuanian-numeric, lithuanian-keyboard, malayalam-inscript, rfc1345, russian-computer, sgml, slovenian, tamil-inscript, ucs, ukrainian-computer, vietnamese-telex, and welsh.
The following language environments have also been added: Belarusian, Bulgarian, Chinese-EUC-TW, Croatian, French, Georgian, Italian, Latin-6, Latin-7, Latvian, Lithuanian, Malayalam, Russian, Slovenian, Swedish, Tajik, Tamil, UTF-8, Ukrainian, Welsh, and Windows-1255.
In addition, Emacs 22 now includes the Emacs Lisp Reference Manual (see Where can I get documentation on Emacs Lisp?) and the Emacs Lisp Intro.
Consult the Emacs NEWS.22 file for the full list of changes in Emacs 22.