special-display-regexps

special-display-regexps is a variable defined in `window.el'.
Its value is

nil

• This variable is obsolete since 24.3;
  use `display-buffer-alist' instead.
• This variable may be risky if used as a file-local variable.

Documentation:
List of regexps saying which buffers should be displayed specially.
Displaying a buffer with `display-buffer' or `pop-to-buffer', if
any regexp in this list matches its name, displays it specially
using `special-display-function'. `special-display-popup-frame'
(the default for `special-display-function') usually displays
the buffer in a separate frame made with the parameters specified
by `special-display-frame-alist'. If `special-display-function'
has been set to some other function, that function is called with
the buffer as first, and nil as second argument.

Alternatively, an element of this list can be specified as
(REGEXP FRAME-PARAMETERS), where REGEXP is a regexp as above and
FRAME-PARAMETERS an alist of (PARAMETER . VALUE) pairs.
`special-display-popup-frame' will then interpret these pairs as
frame parameters when creating a special frame for a buffer whose
name matches REGEXP, overriding the corresponding values from
`special-display-frame-alist'.

As a special case, if FRAME-PARAMETERS contains (same-window . t)
`special-display-popup-frame' displays buffers matching REGEXP in
the selected window. (same-frame . t) in FRAME-PARAMETERS means
to display such buffers in a window on the selected frame.

If `special-display-function' specifies some other function than
`special-display-popup-frame', that function is called with the
buffer whose name matched REGEXP as first, and FRAME-PARAMETERS
as second argument.

Finally, an element of this list can be also specified as
(REGEXP FUNCTION OTHER-ARGS). `special-display-popup-frame'
will then call FUNCTION with the buffer whose name matched
REGEXP as first, and OTHER-ARGS as second argument.

Any alternative function specified here is responsible for
setting up the quit-restore parameter of the window used.

If this variable appears "not to work", because you added a
name to it but the corresponding buffer is displayed in the
selected window, look at the values of `same-window-buffer-names'
and `same-window-regexps'. Those variables take precedence over
this one.

See also `special-display-buffer-names'.

You can customize this variable.