frame.c

/* Generic frame functions.

Copyright (C) 1993-1995, 1997, 1999-2013 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

#define FRAME_INLINE EXTERN_INLINE

#include <stdio.h>
#include <errno.h>
#include <limits.h>

#include <c-ctype.h>

#include "lisp.h"
#include "character.h"

#ifdef HAVE_WINDOW_SYSTEM
#include TERM_HEADER
#endif /* HAVE_WINDOW_SYSTEM */

#include "buffer.h"
/* These help us bind and responding to switch-frame events.  */
#include "commands.h"
#include "keyboard.h"
#include "frame.h"
#include "blockinput.h"
#include "termchar.h"
#include "termhooks.h"
#include "dispextern.h"
#include "window.h"
#include "font.h"
#ifdef HAVE_WINDOW_SYSTEM
#include "fontset.h"
#endif
#ifdef MSDOS
#include "msdos.h"
#include "dosfns.h"
#endif

#ifdef HAVE_NS
Lisp_Object Qns_parse_geometry;
#endif

Lisp_Object Qframep, Qframe_live_p;
Lisp_Object Qicon, Qmodeline;
Lisp_Object Qonly, Qnone;
Lisp_Object Qx, Qw32, Qpc, Qns;
Lisp_Object Qvisible;
Lisp_Object Qdisplay_type;
static Lisp_Object Qbackground_mode;
Lisp_Object Qnoelisp;

static Lisp_Object Qx_frame_parameter;
Lisp_Object Qx_resource_name;
Lisp_Object Qterminal;

/* Frame parameters (set or reported).  */

Lisp_Object Qauto_raise, Qauto_lower;
Lisp_Object Qborder_color, Qborder_width;
Lisp_Object Qcursor_color, Qcursor_type;
Lisp_Object Qheight, Qwidth;
Lisp_Object Qleft, Qright;
Lisp_Object Qicon_left, Qicon_top, Qicon_type, Qicon_name;
Lisp_Object Qtooltip;
Lisp_Object Qinternal_border_width;
Lisp_Object Qmouse_color;
Lisp_Object Qminibuffer;
Lisp_Object Qscroll_bar_width, Qvertical_scroll_bars;
Lisp_Object Qvisibility;
Lisp_Object Qscroll_bar_foreground, Qscroll_bar_background;
Lisp_Object Qscreen_gamma;
Lisp_Object Qline_spacing;
static Lisp_Object Quser_position, Quser_size;
Lisp_Object Qwait_for_wm;
static Lisp_Object Qwindow_id;
#ifdef HAVE_X_WINDOWS
static Lisp_Object Qouter_window_id;
#endif
Lisp_Object Qparent_id;
Lisp_Object Qtitle, Qname;
static Lisp_Object Qexplicit_name;
Lisp_Object Qunsplittable;
Lisp_Object Qmenu_bar_lines, Qtool_bar_lines, Qtool_bar_position;
Lisp_Object Qleft_fringe, Qright_fringe;
Lisp_Object Qbuffer_predicate;
static Lisp_Object Qbuffer_list, Qburied_buffer_list;
Lisp_Object Qtty_color_mode;
Lisp_Object Qtty, Qtty_type;

Lisp_Object Qfullscreen, Qfullwidth, Qfullheight, Qfullboth, Qmaximized;
Lisp_Object Qsticky;
Lisp_Object Qfont_backend;
Lisp_Object Qalpha;

Lisp_Object Qface_set_after_frame_default;

static Lisp_Object Qdelete_frame_functions;

static Lisp_Object Qgeometry, Qworkarea, Qmm_size, Qframes, Qsource;

#ifdef HAVE_WINDOW_SYSTEM
static void x_report_frame_params (struct frame *, Lisp_Object *);
#endif

/* These setters are used only in this file, so they can be private.  */
static void
fset_buffer_predicate (struct frame *f, Lisp_Object val)
{
  f->buffer_predicate = val;
}
static void
fset_minibuffer_window (struct frame *f, Lisp_Object val)
{
  f->minibuffer_window = val;
}

struct frame *
decode_live_frame (register Lisp_Object frame)
{
  if (NILP (frame))
    frame = selected_frame;
  CHECK_LIVE_FRAME (frame);
  return XFRAME (frame);
}

struct frame *
decode_any_frame (register Lisp_Object frame)
{
  if (NILP (frame))
    frame = selected_frame;
  CHECK_FRAME (frame);
  return XFRAME (frame);
}

bool
window_system_available (struct frame *f)
{
  if (f)
    return FRAME_WINDOW_P (f) || FRAME_MSDOS_P (f);
  else
#ifdef HAVE_WINDOW_SYSTEM
    return x_display_list != NULL;
#else
    return 0;
#endif
}

struct frame *
decode_window_system_frame (Lisp_Object frame)
{
  struct frame *f = decode_live_frame (frame);

  if (!window_system_available (f))
    error ("Window system frame should be used");
  return f;
}

void
check_window_system (struct frame *f)
{
  if (!window_system_available (f))
    error (f ? "Window system frame should be used"
	   : "Window system is not in use or not initialized");
}

static void
set_menu_bar_lines_1 (Lisp_Object window, int n)
{
  struct window *w = XWINDOW (window);

  w->last_modified = 0;
  w->top_line += n;
  w->total_lines -= n;

  /* Handle just the top child in a vertical split.  */
  if (WINDOW_VERTICAL_COMBINATION_P (w))
    set_menu_bar_lines_1 (w->contents, n);
  else if (WINDOW_HORIZONTAL_COMBINATION_P (w))
    /* Adjust all children in a horizontal split.  */
    for (window = w->contents; !NILP (window); window = w->next)
      {
	w = XWINDOW (window);
	set_menu_bar_lines_1 (window, n);
      }
}

void
set_menu_bar_lines (struct frame *f, Lisp_Object value, Lisp_Object oldval)
{
  int nlines;
  int olines = FRAME_MENU_BAR_LINES (f);

  /* Right now, menu bars don't work properly in minibuf-only frames;
     most of the commands try to apply themselves to the minibuffer
     frame itself, and get an error because you can't switch buffers
     in or split the minibuffer window.  */
  if (FRAME_MINIBUF_ONLY_P (f))
    return;

  if (TYPE_RANGED_INTEGERP (int, value))
    nlines = XINT (value);
  else
    nlines = 0;

  if (nlines != olines)
    {
      windows_or_buffers_changed++;
      FRAME_WINDOW_SIZES_CHANGED (f) = 1;
      FRAME_MENU_BAR_LINES (f) = nlines;
      set_menu_bar_lines_1 (f->root_window, nlines - olines);
      adjust_glyphs (f);
    }
}

Lisp_Object Vframe_list;


DEFUN ("framep", Fframep, Sframep, 1, 1, 0,
       doc: /* Return non-nil if OBJECT is a frame.
Value is:
  t for a termcap frame (a character-only terminal),
 'x' for an Emacs frame that is really an X window,
 'w32' for an Emacs frame that is a window on MS-Windows display,
 'ns' for an Emacs frame on a GNUstep or Macintosh Cocoa display,
 'pc' for a direct-write MS-DOS frame.
See also `frame-live-p'.  */)
  (Lisp_Object object)
{
  if (!FRAMEP (object))
    return Qnil;
  switch (XFRAME (object)->output_method)
    {
    case output_initial: /* The initial frame is like a termcap frame. */
    case output_termcap:
      return Qt;
    case output_x_window:
      return Qx;
    case output_w32:
      return Qw32;
    case output_msdos_raw:
      return Qpc;
    case output_ns:
      return Qns;
    default:
      emacs_abort ();
    }
}

DEFUN ("frame-live-p", Fframe_live_p, Sframe_live_p, 1, 1, 0,
       doc: /* Return non-nil if OBJECT is a frame which has not been deleted.
Value is nil if OBJECT is not a live frame.  If object is a live
frame, the return value indicates what sort of terminal device it is
displayed on.  See the documentation of `framep' for possible
return values.  */)
  (Lisp_Object object)
{
  return ((FRAMEP (object)
	   && FRAME_LIVE_P (XFRAME (object)))
	  ? Fframep (object)
	  : Qnil);
}

DEFUN ("window-system", Fwindow_system, Swindow_system, 0, 1, 0,
       doc: /* The name of the window system that FRAME is displaying through.
The value is a symbol:
 nil for a termcap frame (a character-only terminal),
 'x' for an Emacs frame that is really an X window,
 'w32' for an Emacs frame that is a window on MS-Windows display,
 'ns' for an Emacs frame on a GNUstep or Macintosh Cocoa display,
 'pc' for a direct-write MS-DOS frame.

FRAME defaults to the currently selected frame.

Use of this function as a predicate is deprecated.  Instead,
use `display-graphic-p' or any of the other `display-*-p'
predicates which report frame's specific UI-related capabilities.  */)
  (Lisp_Object frame)
{
  Lisp_Object type;
  if (NILP (frame))
    frame = selected_frame;

  type = Fframep (frame);

  if (NILP (type))
    wrong_type_argument (Qframep, frame);

  if (EQ (type, Qt))
    return Qnil;
  else
    return type;
}

struct frame *
make_frame (bool mini_p)
{
  Lisp_Object frame;
  register struct frame *f;
  register Lisp_Object root_window;
  register Lisp_Object mini_window;

  f = allocate_frame ();
  XSETFRAME (frame, f);

  /* Initialize Lisp data.  Note that allocate_frame initializes all
     Lisp data to nil, so do it only for slots which should not be nil.  */
  fset_tool_bar_position (f, Qtop);

  /* Initialize non-Lisp data.  Note that allocate_frame zeroes out all
     non-Lisp data, so do it only for slots which should not be zero.
     To avoid subtle bugs and for the sake of readability, it's better to
     initialize enum members explicitly even if their values are zero.  */
  f->wants_modeline = 1;
  f->garbaged = 1;
  f->has_minibuffer = mini_p;
  f->vertical_scroll_bar_type = vertical_scroll_bar_none;
  f->column_width = 1;  /* !FRAME_WINDOW_P value */
  f->line_height = 1;  /* !FRAME_WINDOW_P value */
#ifdef HAVE_WINDOW_SYSTEM
  f->want_fullscreen = FULLSCREEN_NONE;
#endif

  root_window = make_window ();
  if (mini_p)
    {
      mini_window = make_window ();
      wset_next (XWINDOW (root_window), mini_window);
      wset_prev (XWINDOW (mini_window), root_window);
      XWINDOW (mini_window)->mini = 1;
      wset_frame (XWINDOW (mini_window), frame);
      fset_minibuffer_window (f, mini_window);
    }
  else
    {
      mini_window = Qnil;
      wset_next (XWINDOW (root_window), Qnil);
      fset_minibuffer_window (f, Qnil);
    }

  wset_frame (XWINDOW (root_window), frame);

  /* 10 is arbitrary,
     just so that there is "something there."
     Correct size will be set up later with change_frame_size.  */

  SET_FRAME_COLS (f, 10);
  FRAME_LINES (f) = 10;

  XWINDOW (root_window)->total_cols = 10;
  XWINDOW (root_window)->total_lines = mini_p ? 9 : 10;

  if (mini_p)
    {
      XWINDOW (mini_window)->total_cols = 10;
      XWINDOW (mini_window)->top_line = 9;
      XWINDOW (mini_window)->total_lines = 1;
    }

  /* Choose a buffer for the frame's root window.  */
  {
    Lisp_Object buf = Fcurrent_buffer ();

    /* If current buffer is hidden, try to find another one.  */
    if (BUFFER_HIDDEN_P (XBUFFER (buf)))
      buf = other_buffer_safely (buf);

    /* Use set_window_buffer, not Fset_window_buffer, and don't let
       hooks be run by it.  The reason is that the whole frame/window
       arrangement is not yet fully initialized at this point.  Windows
       don't have the right size, glyph matrices aren't initialized
       etc.  Running Lisp functions at this point surely ends in a
       SEGV.  */
    set_window_buffer (root_window, buf, 0, 0);
    fset_buffer_list (f, list1 (buf));
  }

  if (mini_p)
    set_window_buffer (mini_window,
		       (NILP (Vminibuffer_list)
			? get_minibuffer (0)
			: Fcar (Vminibuffer_list)),
		       0, 0);

  fset_root_window (f, root_window);
  fset_selected_window (f, root_window);
  /* Make sure this window seems more recently used than
     a newly-created, never-selected window.  */
  XWINDOW (f->selected_window)->use_time = ++window_select_count;

  return f;
}

#ifdef HAVE_WINDOW_SYSTEM
/* Make a frame using a separate minibuffer window on another frame.
   MINI_WINDOW is the minibuffer window to use.  nil means use the
   default (the global minibuffer).  */

struct frame *
make_frame_without_minibuffer (register Lisp_Object mini_window, KBOARD *kb, Lisp_Object display)
{
  register struct frame *f;
  struct gcpro gcpro1;

  if (!NILP (mini_window))
    CHECK_LIVE_WINDOW (mini_window);

  if (!NILP (mini_window)
      && FRAME_KBOARD (XFRAME (XWINDOW (mini_window)->frame)) != kb)
    error ("Frame and minibuffer must be on the same terminal");

  /* Make a frame containing just a root window.  */
  f = make_frame (0);

  if (NILP (mini_window))
    {
      /* Use default-minibuffer-frame if possible.  */
      if (!FRAMEP (KVAR (kb, Vdefault_minibuffer_frame))
	  || ! FRAME_LIVE_P (XFRAME (KVAR (kb, Vdefault_minibuffer_frame))))
	{
          Lisp_Object frame_dummy;

          XSETFRAME (frame_dummy, f);
          GCPRO1 (frame_dummy);
	  /* If there's no minibuffer frame to use, create one.  */
	  kset_default_minibuffer_frame
	    (kb, call1 (intern ("make-initial-minibuffer-frame"), display));
          UNGCPRO;
	}

      mini_window
	= XFRAME (KVAR (kb, Vdefault_minibuffer_frame))->minibuffer_window;
    }

  fset_minibuffer_window (f, mini_window);

  /* Make the chosen minibuffer window display the proper minibuffer,
     unless it is already showing a minibuffer.  */
  if (NILP (Fmemq (XWINDOW (mini_window)->contents, Vminibuffer_list)))
    /* Use set_window_buffer instead of Fset_window_buffer (see
       discussion of bug#11984, bug#12025, bug#12026).  */
    set_window_buffer (mini_window,
		       (NILP (Vminibuffer_list)
			? get_minibuffer (0)
			: Fcar (Vminibuffer_list)), 0, 0);
  return f;
}

/* Make a frame containing only a minibuffer window.  */

struct frame *
make_minibuffer_frame (void)
{
  /* First make a frame containing just a root window, no minibuffer.  */

  register struct frame *f = make_frame (0);
  register Lisp_Object mini_window;
  register Lisp_Object frame;

  XSETFRAME (frame, f);

  f->auto_raise = 0;
  f->auto_lower = 0;
  f->no_split = 1;
  f->wants_modeline = 0;
  f->has_minibuffer = 1;

  /* Now label the root window as also being the minibuffer.
     Avoid infinite looping on the window chain by marking next pointer
     as nil. */

  mini_window = f->root_window;
  fset_minibuffer_window (f, mini_window);
  XWINDOW (mini_window)->mini = 1;
  wset_next (XWINDOW (mini_window), Qnil);
  wset_prev (XWINDOW (mini_window), Qnil);
  wset_frame (XWINDOW (mini_window), frame);

  /* Put the proper buffer in that window.  */

  /* Use set_window_buffer instead of Fset_window_buffer (see
     discussion of bug#11984, bug#12025, bug#12026).  */
  set_window_buffer (mini_window,
		     (NILP (Vminibuffer_list)
		      ? get_minibuffer (0)
		      : Fcar (Vminibuffer_list)), 0, 0);
  return f;
}
#endif /* HAVE_WINDOW_SYSTEM */

/* Construct a frame that refers to a terminal.  */

static printmax_t tty_frame_count;

struct frame *
make_initial_frame (void)
{
  struct frame *f;
  struct terminal *terminal;
  Lisp_Object frame;

  eassert (initial_kboard);

  /* The first call must initialize Vframe_list.  */
  if (! (NILP (Vframe_list) || CONSP (Vframe_list)))
    Vframe_list = Qnil;

  terminal = init_initial_terminal ();

  f = make_frame (1);
  XSETFRAME (frame, f);

  Vframe_list = Fcons (frame, Vframe_list);

  tty_frame_count = 1;
  fset_name (f, build_pure_c_string ("F1"));

  SET_FRAME_VISIBLE (f, 1);

  f->output_method = terminal->type;
  f->terminal = terminal;
  f->terminal->reference_count++;
  f->output_data.nothing = 0;

  FRAME_FOREGROUND_PIXEL (f) = FACE_TTY_DEFAULT_FG_COLOR;
  FRAME_BACKGROUND_PIXEL (f) = FACE_TTY_DEFAULT_BG_COLOR;

  FRAME_VERTICAL_SCROLL_BAR_TYPE (f) = vertical_scroll_bar_none;

  /* The default value of menu-bar-mode is t.  */
  set_menu_bar_lines (f, make_number (1), Qnil);

  if (!noninteractive)
    init_frame_faces (f);

  return f;
}


static struct frame *
make_terminal_frame (struct terminal *terminal)
{
  register struct frame *f;
  Lisp_Object frame;
  char name[sizeof "F" + INT_STRLEN_BOUND (printmax_t)];

  if (!terminal->name)
    error ("Terminal is not live, can't create new frames on it");

  f = make_frame (1);

  XSETFRAME (frame, f);
  Vframe_list = Fcons (frame, Vframe_list);

  fset_name (f, make_formatted_string (name, "F%"pMd, ++tty_frame_count));

  SET_FRAME_VISIBLE (f, 1);

  f->terminal = terminal;
  f->terminal->reference_count++;
#ifdef MSDOS
  f->output_data.tty->display_info = &the_only_display_info;
  if (!inhibit_window_system
      && (!FRAMEP (selected_frame) || !FRAME_LIVE_P (XFRAME (selected_frame))
	  || XFRAME (selected_frame)->output_method == output_msdos_raw))
    f->output_method = output_msdos_raw;
  else
    f->output_method = output_termcap;
#else /* not MSDOS */
  f->output_method = output_termcap;
  create_tty_output (f);
  FRAME_FOREGROUND_PIXEL (f) = FACE_TTY_DEFAULT_FG_COLOR;
  FRAME_BACKGROUND_PIXEL (f) = FACE_TTY_DEFAULT_BG_COLOR;
#endif /* not MSDOS */

  FRAME_VERTICAL_SCROLL_BAR_TYPE (f) = vertical_scroll_bar_none;
  FRAME_MENU_BAR_LINES(f) = NILP (Vmenu_bar_mode) ? 0 : 1;

  /* Set the top frame to the newly created frame. */
  if (FRAMEP (FRAME_TTY (f)->top_frame)
      && FRAME_LIVE_P (XFRAME (FRAME_TTY (f)->top_frame)))
    SET_FRAME_VISIBLE (XFRAME (FRAME_TTY (f)->top_frame), 2); /* obscured */

  FRAME_TTY (f)->top_frame = frame;

  if (!noninteractive)
    init_frame_faces (f);

  return f;
}

/* Get a suitable value for frame parameter PARAMETER for a newly
   created frame, based on (1) the user-supplied frame parameter
   alist SUPPLIED_PARMS, and (2) CURRENT_VALUE.  */

static Lisp_Object
get_future_frame_param (Lisp_Object parameter,
                        Lisp_Object supplied_parms,
                        char *current_value)
{
  Lisp_Object result;

  result = Fassq (parameter, supplied_parms);
  if (NILP (result))
    result = Fassq (parameter, XFRAME (selected_frame)->param_alist);
  if (NILP (result) && current_value != NULL)
    result = build_string (current_value);
  if (!NILP (result) && !STRINGP (result))
    result = XCDR (result);
  if (NILP (result) || !STRINGP (result))
    result = Qnil;

  return result;
}

DEFUN ("make-terminal-frame", Fmake_terminal_frame, Smake_terminal_frame,
       1, 1, 0,
       doc: /* Create an additional terminal frame, possibly on another terminal.
This function takes one argument, an alist specifying frame parameters.

You can create multiple frames on a single text terminal, but only one
of them (the selected terminal frame) is actually displayed.

In practice, generally you don't need to specify any parameters,
except when you want to create a new frame on another terminal.
In that case, the `tty' parameter specifies the device file to open,
and the `tty-type' parameter specifies the terminal type.  Example:

   (make-terminal-frame '((tty . "/dev/pts/5") (tty-type . "xterm")))

Note that changing the size of one terminal frame automatically
affects all frames on the same terminal device.  */)
  (Lisp_Object parms)
{
  struct frame *f;
  struct terminal *t = NULL;
  Lisp_Object frame, tem;
  struct frame *sf = SELECTED_FRAME ();

#ifdef MSDOS
  if (sf->output_method != output_msdos_raw
      && sf->output_method != output_termcap)
    emacs_abort ();
#else /* not MSDOS */

#ifdef WINDOWSNT                           /* This should work now! */
  if (sf->output_method != output_termcap)
    error ("Not using an ASCII terminal now; cannot make a new ASCII frame");
#endif
#endif /* not MSDOS */

  {
    Lisp_Object terminal;

    terminal = Fassq (Qterminal, parms);
    if (CONSP (terminal))
      {
        terminal = XCDR (terminal);
        t = get_terminal (terminal, 1);
      }
#ifdef MSDOS
    if (t && t != the_only_display_info.terminal)
      /* msdos.c assumes a single tty_display_info object.  */
      error ("Multiple terminals are not supported on this platform");
    if (!t)
      t = the_only_display_info.terminal;
#endif
  }

  if (!t)
    {
      char *name = 0, *type = 0;
      Lisp_Object tty, tty_type;

      tty = get_future_frame_param
        (Qtty, parms, (FRAME_TERMCAP_P (XFRAME (selected_frame))
                       ? FRAME_TTY (XFRAME (selected_frame))->name
                       : NULL));
      if (!NILP (tty))
        {
          name = alloca (SBYTES (tty) + 1);
          memcpy (name, SSDATA (tty), SBYTES (tty));
          name[SBYTES (tty)] = 0;
        }

      tty_type = get_future_frame_param
        (Qtty_type, parms, (FRAME_TERMCAP_P (XFRAME (selected_frame))
                            ? FRAME_TTY (XFRAME (selected_frame))->type
                            : NULL));
      if (!NILP (tty_type))
        {
          type = alloca (SBYTES (tty_type) + 1);
          memcpy (type, SSDATA (tty_type), SBYTES (tty_type));
          type[SBYTES (tty_type)] = 0;
        }

      t = init_tty (name, type, 0); /* Errors are not fatal. */
    }

  f = make_terminal_frame (t);

  {
    int width, height;
    get_tty_size (fileno (FRAME_TTY (f)->input), &width, &height);
    change_frame_size (f, height, width, 0, 0, 0);
  }

  adjust_glyphs (f);
  calculate_costs (f);
  XSETFRAME (frame, f);
  Fmodify_frame_parameters (frame, parms);
  Fmodify_frame_parameters
    (frame, list1 (Fcons (Qtty_type,
			  build_string (t->display_info.tty->type))));
  if (t->display_info.tty->name != NULL)
    Fmodify_frame_parameters
      (frame, list1 (Fcons (Qtty,
			    build_string (t->display_info.tty->name))));
  else
    Fmodify_frame_parameters (frame, list1 (Fcons (Qtty, Qnil)));

  /* Make the frame face alist be frame-specific, so that each
     frame could change its face definitions independently.  */
  fset_face_alist (f, Fcopy_alist (sf->face_alist));
  /* Simple Fcopy_alist isn't enough, because we need the contents of
     the vectors which are the CDRs of associations in face_alist to
     be copied as well.  */
  for (tem = f->face_alist; CONSP (tem); tem = XCDR (tem))
    XSETCDR (XCAR (tem), Fcopy_sequence (XCDR (XCAR (tem))));
  return frame;
}


/* Perform the switch to frame FRAME.

   If FRAME is a switch-frame event `(switch-frame FRAME1)', use
   FRAME1 as frame.

   If TRACK is non-zero and the frame that currently has the focus
   redirects its focus to the selected frame, redirect that focused
   frame's focus to FRAME instead.

   FOR_DELETION non-zero means that the selected frame is being
   deleted, which includes the possibility that the frame's terminal
   is dead.

   The value of NORECORD is passed as argument to Fselect_window.  */

Lisp_Object
do_switch_frame (Lisp_Object frame, int track, int for_deletion, Lisp_Object norecord)
{
  struct frame *sf = SELECTED_FRAME ();

  /* If FRAME is a switch-frame event, extract the frame we should
     switch to.  */
  if (CONSP (frame)
      && EQ (XCAR (frame), Qswitch_frame)
      && CONSP (XCDR (frame)))
    frame = XCAR (XCDR (frame));

  /* This used to say CHECK_LIVE_FRAME, but apparently it's possible for
     a switch-frame event to arrive after a frame is no longer live,
     especially when deleting the initial frame during startup.  */
  CHECK_FRAME (frame);
  if (! FRAME_LIVE_P (XFRAME (frame)))
    return Qnil;

  if (sf == XFRAME (frame))
    return frame;

  /* This is too greedy; it causes inappropriate focus redirection
     that's hard to get rid of.  */
#if 0
  /* If a frame's focus has been redirected toward the currently
     selected frame, we should change the redirection to point to the
     newly selected frame.  This means that if the focus is redirected
     from a minibufferless frame to a surrogate minibuffer frame, we
     can use `other-window' to switch between all the frames using
     that minibuffer frame, and the focus redirection will follow us
     around.  */