25:  What is different about Emacs 19?

  To find out what has changed in recent versions, type C-h n (M-x
  view-emacs-news).  The oldest changes are at the bottom of the file, so
  you might want to read it starting there, rather than at the top.

  The most obvious changes have to do with the user interface -- Emacs 19
  is fully X-aware, and provides pull-down menus (see question 63) and
  scroll bars.  Emacs 19 also supports fonts and colors, including
  context-specific highlighting of source code and other types of buffers
  (see question 65).

  Other changes include a line number mode, which displays the current line
  number in the mode line, and default bindings for arrow and paging keys
  that work.

  Lower-level changes include a smarter memory allocation scheme (Emacs now
  returns memory to the operating system when you kill buffers), a better
  byte-compiler, and a source-level Emacs Lisp debugger.

  There are also a number of new Lisp packages, ranging from dunnet (an
  Adventure-like program) to mldrag (allows you to drag the mode line up
  and down with mouse buttons) to gud (Grand Unified Debugger mode, for
  many flavors of debuggers).  A number of older Lisp packages, such as
  Gnus, SuperCite and the calendar/diary, have been updated and enhanced to
  work with Emacs 19, and are now included with the standard distribution.