Start `emacs -Q`
(make the window full screen height, 80 columns wide)
M-x shell RET
(in the shell buffer)
$ cd /tmp
$ mkdir foo
$ cd foo
$ touch aa.txt ab.txt cc.txt dd.txt ee.txt ff.txt gg.txt hh.txt ii.txt jj.txt kk.txt ll.txt mm.txt nn.txt oo.txt pp.txt qq.txt rr.txt ss.txt tt.txt uu.txt vv.txt ww.txt xx.txt yy.txt zz.txt
$ ls -l
$ ls -l
(this is just to fill the buffer with output.  now your shell prompt
should be the last line at the bottom of the frame, if not, hit C-l a
few times until it is.)
$ cat a<TAB>

With `(setq split-window-keep-point t)` you will see the window split,
with the top window scrolled to leave point just after the `a` in the
middle of the window.  The bottom window will have the completions for
aa.txt and ab.txt

With `(setq split-window-keep-point nil)` you will not get any window
split, but point will jump someplace higher up in the window (e.g. for
me it jumps to just after the gg.txt line).


In GNU Emacs 24.3.1 (x86_64-pc-linux-gnu, GTK+ Version 3.8.2)
 of 2013-06-14 on komainu, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11303000
System Description:	Ubuntu Saucy Salamander (development branch)

Configured using:
 `configure '--build' 'x86_64-linux-gnu' '--build' 'x86_64-linux-gnu'
 '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib'
 '--localstatedir=/var/lib' '--infodir=/usr/share/info'
 '--mandir=/usr/share/man' '--with-pop=yes'
 '--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.3/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.3/site-lisp:/usr/share/emacs/site-lisp'
 '--with-crt-dir=/usr/lib/x86_64-linux-gnu' '--with-x=yes'
 '--with-x-toolkit=gtk3' '--with-toolkit-scroll-bars'
 'build_alias=x86_64-linux-gnu' 'CFLAGS=-g -O2 -fstack-protector
 --param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wall'
 'LDFLAGS=-Wl,-Bsymbolic-functions -Wl,-z,relro'
 'CPPFLAGS=-D_FORTIFY_SOURCE=2''

Important settings:
  value of $LC_COLLATE: en_US.UTF-8
  value of $LC_CTYPE: en_US.UTF-8
  value of $LC_MESSAGES: en_US.UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Shell

Minor modes in effect:
  erc-notifications-mode: t
  delete-selection-mode: t
  icomplete-mode: t
  shell-dirtrack-mode: t
  erc-spelling-mode: t
  erc-services-mode: t
  erc-ring-mode: t
  erc-networks-mode: t
  erc-netsplit-mode: t
  erc-menu-mode: t
  erc-list-mode: t
  erc-pcomplete-mode: t
  erc-button-mode: t
  erc-fill-mode: t
  erc-stamp-mode: t
  erc-autojoin-mode: t
  show-paren-mode: t
  savehist-mode: t
  rcirc-track-minor-mode: t
  global-whitespace-mode: t
  erc-track-mode: t
  erc-track-minor-mode: t
  erc-match-mode: t
  erc-irccontrols-mode: t
  erc-noncommands-mode: t
  erc-move-to-prompt-mode: t
  erc-readonly-mode: t
  desktop-save-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t