4.4 What is different about Emacs 24?

• Emacs now includes a package manager. Type M-x list-packages to get started. You can use this to download and automatically install many more Lisp packages.
• Emacs Lisp now supports lexical binding on a per-file basis. In lexical binding, variable references must be located textually within the binding construct. This contrasts with dynamic binding, where programs can refer to variables defined outside their local textual scope. A Lisp file can use a local variable setting of lexical-binding: t to indicate that the contents should be interpreted using lexical binding. See the Emacs Lisp Reference Manual for more details.
• Some human languages, such as English, are written from left to right. Others, such as Arabic, are written from right to left. Emacs now has support for any mixture of these forms—this is “bidirectional text”.
• Handling of text selections has been improved, and now integrates better with external clipboards.
• A new command customize-themes allows you to easily change the appearance of your Emacs.
• Emacs can be compiled with the GTK+ 3 toolkit.
• Support for several new external libraries can be included at compile time:
  • “Security-Enhanced Linux” (SELinux) is a Linux kernel feature that provides more sophisticated file access controls than ordinary “Unix-style” file permissions.
  • The ImageMagick display library. This allows you to display many more image format in Emacs, as well as carry out transformations such as rotations.
  • The GnuTLS library for secure network communications. Emacs uses this transparently for email if your mail server supports it.
  • The libxml2 library for parsing XML structures.
• Much more flexibility in the handling of windows and buffer display.

As always, consult the NEWS file for more information.