frame.c

/* Generic frame functions.
   Copyright (C) 1993, 1994, 1995 Free Software Foundation.

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 2, 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; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include <config.h>

#include <stdio.h>
#include "lisp.h"
#include "frame.h"
#include "termhooks.h"
#include "window.h"
#ifdef MSDOS
#include "msdos.h"
#endif

#ifdef MULTI_FRAME

#include "buffer.h"

/* These help us bind and responding to switch-frame events.  */
#include "commands.h"
#include "keyboard.h"

Lisp_Object Vemacs_iconified;
Lisp_Object Vframe_list;
Lisp_Object Vterminal_frame;
Lisp_Object Vdefault_frame_alist;

/* Evaluate this expression to rebuild the section of syms_of_frame
   that initializes and staticpros the symbols declared below.  Note
   that Emacs 18 has a bug that keeps C-x C-e from being able to
   evaluate this expression.

(progn
  ;; Accumulate a list of the symbols we want to initialize from the
  ;; declarations at the top of the file.
  (goto-char (point-min))
  (search-forward "/\*&&& symbols declared here &&&*\/\n")
  (let (symbol-list)
    (while (looking-at "Lisp_Object \\(Q[a-z_]+\\)")
      (setq symbol-list
	    (cons (buffer-substring (match-beginning 1) (match-end 1))
		  symbol-list))
      (forward-line 1))
    (setq symbol-list (nreverse symbol-list))
    ;; Delete the section of syms_of_... where we initialize the symbols.
    (search-forward "\n  /\*&&& init symbols here &&&*\/\n")
    (let ((start (point)))
      (while (looking-at "^  Q")
	(forward-line 2))
      (kill-region start (point)))
    ;; Write a new symbol initialization section.
    (while symbol-list
      (insert (format "  %s = intern (\"" (car symbol-list)))
      (let ((start (point)))
	(insert (substring (car symbol-list) 1))
	(subst-char-in-region start (point) ?_ ?-))
      (insert (format "\");\n  staticpro (&%s);\n" (car symbol-list)))
      (setq symbol-list (cdr symbol-list)))))
  */        

/*&&& symbols declared here &&&*/
Lisp_Object Qframep;
Lisp_Object Qframe_live_p;
Lisp_Object Qheight;
Lisp_Object Qicon;
Lisp_Object Qminibuffer;
Lisp_Object Qmodeline;
Lisp_Object Qname;
Lisp_Object Qonly;
Lisp_Object Qunsplittable;
Lisp_Object Qmenu_bar_lines;
Lisp_Object Qwidth;
Lisp_Object Qx;
Lisp_Object Qvisible;
Lisp_Object Qbuffer_predicate;

extern Lisp_Object Vminibuffer_list;
extern Lisp_Object get_minibuffer ();
extern Lisp_Object Fhandle_switch_frame ();
extern Lisp_Object Fredirect_frame_focus ();
extern Lisp_Object x_get_focus_frame ();

DEFUN ("framep", Fframep, Sframep, 1, 1, 0,
  "Return non-nil if OBJECT is a frame.\n\
Value is t for a termcap frame (a character-only terminal),\n\
`x' for an Emacs frame that is really an X window,\n\
`pc' for a direct-write MS-DOS frame.\n\
See also `frame-live-p'.")
  (object)
     Lisp_Object object;
{
  if (!FRAMEP (object))
    return Qnil;
  switch (XFRAME (object)->output_method)
    {
    case output_termcap:
      return Qt;
    case output_x_window:
      return Qx;
      /* The `pc' case is in the Fframep below.  */
    default:
      abort ();
    }
}

DEFUN ("frame-live-p", Fframe_live_p, Sframe_live_p, 1, 1, 0,
  "Return non-nil if OBJECT is a frame which has not been deleted.\n\
Value is nil if OBJECT is not a live frame.  If object is a live\n\
frame, the return value indicates what sort of output device it is\n\
displayed on.  Value is t for a termcap frame (a character-only\n\
terminal), `x' for an Emacs frame being displayed in an X window.")
  (object)
     Lisp_Object object;
{
  return ((FRAMEP (object)
	   && FRAME_LIVE_P (XFRAME (object)))
	  ? Fframep (object)
	  : Qnil);
}

struct frame *
make_frame (mini_p)
     int mini_p;
{
  Lisp_Object frame;
  register struct frame *f;
  register Lisp_Object root_window;
  register Lisp_Object mini_window;
  register struct Lisp_Vector *vec;
  int i;

  vec = allocate_vectorlike ((EMACS_INT) VECSIZE (struct frame));
  for (i = 0; i < VECSIZE (struct frame); i++)
    XSETFASTINT (vec->contents[i], 0);
  vec->size = VECSIZE (struct frame);
  f = (struct frame *)vec;
  XSETFRAME (frame, f);

  f->cursor_x = 0;
  f->cursor_y = 0;
  f->current_glyphs = 0;
  f->desired_glyphs = 0;
  f->visible = 0;
  f->async_visible = 0;
  f->display.nothing = 0;
  f->iconified = 0;
  f->async_iconified = 0;
  f->wants_modeline = 1;
  f->auto_raise = 0;
  f->auto_lower = 0;
  f->no_split = 0;
  f->garbaged = 0;
  f->has_minibuffer = mini_p;
  f->focus_frame = Qnil;
  f->explicit_name = 0;
  f->can_have_scroll_bars = 0;
  f->has_vertical_scroll_bars = 0;
  f->param_alist = Qnil;
  f->scroll_bars = Qnil;
  f->condemned_scroll_bars = Qnil;
  f->face_alist = Qnil;
  f->menu_bar_items = Qnil;
  f->menu_bar_vector = Qnil;
  f->menu_bar_items_used = 0;
  f->buffer_predicate = Qnil;
#ifdef MULTI_KBOARD
  f->kboard = initial_kboard;
#endif
  f->namebuf = 0;

  root_window = make_window ();
  if (mini_p)
    {
      mini_window = make_window ();
      XWINDOW (root_window)->next = mini_window;
      XWINDOW (mini_window)->prev = root_window;
      XWINDOW (mini_window)->mini_p = Qt;
      XWINDOW (mini_window)->frame = frame;
      f->minibuffer_window = mini_window;
    }
  else
    {
      mini_window = Qnil;
      XWINDOW (root_window)->next = Qnil;
      f->minibuffer_window = Qnil;
    }

  XWINDOW (root_window)->frame = frame;

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

  f->width = 10;
  f->height = 10;

  XSETFASTINT (XWINDOW (root_window)->width, 10);
  XSETFASTINT (XWINDOW (root_window)->height, (mini_p ? 9 : 10));

  if (mini_p)
    {
      XSETFASTINT (XWINDOW (mini_window)->width, 10);
      XSETFASTINT (XWINDOW (mini_window)->top, 9);
      XSETFASTINT (XWINDOW (mini_window)->height, 1);
    }

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

    XWINDOW (root_window)->buffer = Qt;
    buf = Fcurrent_buffer ();
    /* If buf is a 'hidden' buffer (i.e. one whose name starts with
       a space), try to find another one.  */
    if (XSTRING (Fbuffer_name (buf))->data[0] == ' ')
      buf = Fother_buffer (buf, Qnil);
    Fset_window_buffer (root_window, buf);
  }

  if (mini_p)
    {
      XWINDOW (mini_window)->buffer = Qt;
      Fset_window_buffer (mini_window,
			  (NILP (Vminibuffer_list)
			   ? get_minibuffer (0)
			   : Fcar (Vminibuffer_list)));
    }

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

  return f;
}

/* 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 (mini_window, kb, display)
     register Lisp_Object mini_window;
     KBOARD *kb;
     Lisp_Object display;
{
  register struct frame *f;

  if (!NILP (mini_window))
    CHECK_LIVE_WINDOW (mini_window, 0);

#ifdef MULTI_KBOARD
  if (!NILP (mini_window)
      && XFRAME (XWINDOW (mini_window)->frame)->kboard != kb)
    error ("frame and minibuffer must be on the same display");
#endif

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

  if (NILP (mini_window))
    {
      /* Use default-minibuffer-frame if possible.  */
      if (!FRAMEP (kb->Vdefault_minibuffer_frame)
	  || ! FRAME_LIVE_P (XFRAME (kb->Vdefault_minibuffer_frame)))
	{
	  /* If there's no minibuffer frame to use, create one.  */
	  kb->Vdefault_minibuffer_frame
	    = call1 (intern ("make-initial-minibuffer-frame"), display);
	}
      mini_window = XFRAME (kb->Vdefault_minibuffer_frame)->minibuffer_window;
    }
  /* Install the chosen minibuffer window, with proper buffer.  */
  f->minibuffer_window = mini_window;
  Fset_window_buffer (mini_window,
		      (NILP (Vminibuffer_list)
		       ? get_minibuffer (0)
		       : Fcar (Vminibuffer_list)));
  return f;
}

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

struct frame *
make_minibuffer_frame ()
{
  /* 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->minibuffer_window = f->root_window;
  XWINDOW (mini_window)->mini_p = Qt;
  XWINDOW (mini_window)->next = Qnil;
  XWINDOW (mini_window)->prev = Qnil;
  XWINDOW (mini_window)->frame = frame;

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

  Fset_window_buffer (mini_window,
		      (NILP (Vminibuffer_list)
		       ? get_minibuffer (0)
		       : Fcar (Vminibuffer_list)));
  return f;
}

/* Construct a frame that refers to the terminal (stdin and stdout).  */

static int terminal_frame_count;

struct frame *
make_terminal_frame ()
{
  register struct frame *f;
  Lisp_Object frame;
  char name[20];

#ifdef MULTI_KBOARD
  if (!initial_kboard)
    {
      initial_kboard = (KBOARD *) xmalloc (sizeof (KBOARD));
      init_kboard (initial_kboard);
      initial_kboard->next_kboard = all_kboards;
      all_kboards = initial_kboard;
    }
#endif

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

  f = make_frame (1);

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

  terminal_frame_count++;
  if (terminal_frame_count == 1)
    {
      f->name = build_string ("Emacs");
    }
  else
    {
      sprintf (name, "Emacs-%d", terminal_frame_count);
      f->name = build_string (name);
    }

  f->visible = 1;		/* FRAME_SET_VISIBLE wd set frame_garbaged. */
  f->async_visible = 1;		/* Don't let visible be cleared later. */
  f->display.nothing = 1;	/* Nonzero means frame isn't deleted.  */
  return f;
}

DEFUN ("make-terminal-frame", Fmake_terminal_frame, Smake_terminal_frame,
       1, 1, 0, "Create an additional terminal frame.\n\
You can create multiple frames on a text-only terminal in this way.\n\
Only the selected terminal frame is actually displayed.\n\
This function takes one argument, an alist specifying frame parameters.\n\
In practice, generally you don't need to specify any parameters.\n\
Note that changing the size of one terminal frame automatically affects all.")
  (parms)
     Lisp_Object parms;
{
  struct frame *f;
  Lisp_Object frame;

  if (selected_frame->output_method != output_termcap)
    error ("Not using an ASCII terminal now; cannot make a new ASCII frame");

  f = make_terminal_frame ();
  change_frame_size (f, FRAME_HEIGHT (selected_frame),
		     FRAME_WIDTH (selected_frame), 0, 0);
  remake_frame_glyphs (f);
  calculate_costs (f);
  XSETFRAME (frame, f);
  Fmodify_frame_parameters (frame, parms);
  return frame;
}

Lisp_Object
do_switch_frame (frame, no_enter, track)
     Lisp_Object frame, no_enter;
     int track;
{
  /* If FRAME is a switch-frame event, extract the frame we should
     switch to.  */
  if (CONSP (frame)
      && EQ (XCONS (frame)->car, Qswitch_frame)
      && CONSP (XCONS (frame)->cdr))
    frame = XCONS (XCONS (frame)->cdr)->car;

  /* 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, 0);
  if (! FRAME_LIVE_P (XFRAME (frame)))
    return Qnil;

  if (selected_frame == 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.  */
  if (track)
    {
      Lisp_Object tail;

      for (tail = Vframe_list; CONSP (tail); tail = XCONS (tail)->cdr)
	{
	  Lisp_Object focus;

	  if (!FRAMEP (XCONS (tail)->car))
	    abort ();

	  focus = FRAME_FOCUS_FRAME (XFRAME (XCONS (tail)->car));

	  if (FRAMEP (focus) && XFRAME (focus) == selected_frame)
	    Fredirect_frame_focus (XCONS (tail)->car, frame);
	}
    }
#else /* ! 0 */
  /* Instead, apply it only to the frame we're pointing to.  */
#ifdef HAVE_X_WINDOWS
  if (track && FRAME_X_P (XFRAME (frame)))
    {
      Lisp_Object focus, xfocus;

      xfocus = x_get_focus_frame (XFRAME (frame));
      if (FRAMEP (xfocus))
	{
	  focus = FRAME_FOCUS_FRAME (XFRAME (xfocus));
	  if (FRAMEP (focus) && XFRAME (focus) == selected_frame)
	    Fredirect_frame_focus (xfocus, frame);
	}
    }
#endif /* HAVE_X_WINDOWS */
#endif /* ! 0 */

  if (FRAME_TERMCAP_P (XFRAME (frame)))
    {
      /* Since frames on an ASCII terminal share the same display area,
	 switching means we must redisplay the whole thing.  */
      windows_or_buffers_changed++;
      SET_FRAME_GARBAGED (XFRAME (frame));
      XSETFRAME (Vterminal_frame, frame);
    }

  selected_frame = XFRAME (frame);
  if (! FRAME_MINIBUF_ONLY_P (selected_frame))
    last_nonminibuf_frame = selected_frame;

  Fselect_window (XFRAME (frame)->selected_window);
  choose_minibuf_frame ();

  /* We want to make sure that the next event generates a frame-switch
     event to the appropriate frame.  This seems kludgy to me, but
     before you take it out, make sure that evaluating something like
     (select-window (frame-root-window (new-frame))) doesn't end up
     with your typing being interpreted in the new frame instead of
     the one you're actually typing in.  */
  internal_last_event_frame = Qnil;

  return frame;
}

DEFUN ("select-frame", Fselect_frame, Sselect_frame, 1, 2, "e",
  "Select the frame FRAME.\n\
Subsequent editing commands apply to its selected window.\n\
The selection of FRAME lasts until the next time the user does\n\
something to select a different frame, or until the next time this\n\
function is called.")
  (frame, no_enter)
    Lisp_Object frame, no_enter;
{
  return do_switch_frame (frame, no_enter, 1);
}


DEFUN ("handle-switch-frame", Fhandle_switch_frame, Shandle_switch_frame, 1, 2, "e",
  "Handle a switch-frame event EVENT.\n\
Switch-frame events are usually bound to this function.\n\
A switch-frame event tells Emacs that the window manager has requested\n\
that the user's events be directed to the frame mentioned in the event.\n\
This function selects the selected window of the frame of EVENT.\n\
\n\
If EVENT is frame object, handle it as if it were a switch-frame event\n\
to that frame.")
  (frame, no_enter)
     Lisp_Object frame, no_enter;
{
  /* Preserve prefix arg that the command loop just cleared.  */
  current_kboard->Vprefix_arg = Vcurrent_prefix_arg;
  return do_switch_frame (frame, no_enter, 0);
}

DEFUN ("ignore-event", Fignore_event, Signore_event, 0, 0, "",
  "Do nothing, but preserve any prefix argument already specified.\n\
This is a suitable binding for iconify-frame and make-frame-visible.")
     ()
{
  current_kboard->Vprefix_arg = Vcurrent_prefix_arg;
  return Qnil;
}

DEFUN ("selected-frame", Fselected_frame, Sselected_frame, 0, 0, 0,
  "Return the frame that is now selected.")
  ()
{
  Lisp_Object tem;
  XSETFRAME (tem, selected_frame);
  return tem;
}

DEFUN ("window-frame", Fwindow_frame, Swindow_frame, 1, 1, 0,
  "Return the frame object that window WINDOW is on.")
  (window)
     Lisp_Object window;
{
  CHECK_LIVE_WINDOW (window, 0);
  return XWINDOW (window)->frame;
}

DEFUN ("frame-first-window", Fframe_first_window, Sframe_first_window, 0, 1, 0,
  "Returns the topmost, leftmost window of FRAME.\n\
If omitted, FRAME defaults to the currently selected frame.")
  (frame)
     Lisp_Object frame;
{
  Lisp_Object w;

  if (NILP (frame))
    w = selected_frame->root_window;
  else
    {
      CHECK_LIVE_FRAME (frame, 0);
      w = XFRAME (frame)->root_window;
    }
  while (NILP (XWINDOW (w)->buffer))
    {
      if (! NILP (XWINDOW (w)->hchild))
	w = XWINDOW (w)->hchild;
      else if (! NILP (XWINDOW (w)->vchild))
	w = XWINDOW (w)->vchild;
      else
	abort ();
    }
  return w;
}

DEFUN ("active-minibuffer-window", Factive_minibuffer_window,
       Sactive_minibuffer_window, 0, 0, 0,
       "Return the currently active minibuffer window, or nil if none.")
  ()
{
  return minibuf_level ? minibuf_window : Qnil;
}

DEFUN ("frame-root-window", Fframe_root_window, Sframe_root_window, 0, 1, 0,
       "Returns the root-window of FRAME.\n\
If omitted, FRAME defaults to the currently selected frame.")
  (frame)
     Lisp_Object frame;
{
  if (NILP (frame))
    XSETFRAME (frame, selected_frame);
  else
    CHECK_LIVE_FRAME (frame, 0);

  return XFRAME (frame)->root_window;
}

DEFUN ("frame-selected-window", Fframe_selected_window,
       Sframe_selected_window, 0, 1, 0,
  "Return the selected window of frame object FRAME.\n\
If omitted, FRAME defaults to the currently selected frame.")
  (frame)
     Lisp_Object frame;
{
  if (NILP (frame))
    XSETFRAME (frame, selected_frame);
  else
    CHECK_LIVE_FRAME (frame, 0);

  return XFRAME (frame)->selected_window;
}

DEFUN ("set-frame-selected-window", Fset_frame_selected_window,
       Sset_frame_selected_window, 2, 2, 0,
  "Set the selected window of frame object FRAME to WINDOW.\n\
If FRAME is nil, the selected frame is used.\n\
If FRAME is the selected frame, this makes WINDOW the selected window.")
  (frame, window)
     Lisp_Object frame, window;
{
  if (NILP (frame))
    XSETFRAME (frame, selected_frame);
  else
    CHECK_LIVE_FRAME (frame, 0);

  CHECK_LIVE_WINDOW (window, 1);

  if (! EQ (frame, WINDOW_FRAME (XWINDOW (window))))
    error ("In `set-frame-selected-window', WINDOW is not on FRAME");

  if (XFRAME (frame) == selected_frame)
    return Fselect_window (window);

  return XFRAME (frame)->selected_window = window;
}

DEFUN ("frame-list", Fframe_list, Sframe_list,
       0, 0, 0,
       "Return a list of all frames.")
  ()
{
  return Fcopy_sequence (Vframe_list);
}

/* Return the next frame in the frame list after FRAME.
   If MINIBUF is nil, exclude minibuffer-only frames.
   If MINIBUF is a window, include only its own frame
   and any frame now using that window as the minibuffer.
   If MINIBUF is `visible', include all visible frames.
   If MINIBUF is 0, include all visible and iconified frames.
   Otherwise, include all frames.  */

Lisp_Object
next_frame (frame, minibuf)
     Lisp_Object frame;
     Lisp_Object minibuf;
{
  Lisp_Object tail;
  int passed = 0;

  /* There must always be at least one frame in Vframe_list.  */
  if (! CONSP (Vframe_list))
    abort ();

  /* If this frame is dead, it won't be in Vframe_list, and we'll loop
     forever.  Forestall that.  */
  CHECK_LIVE_FRAME (frame, 0);

  while (1)
    for (tail = Vframe_list; CONSP (tail); tail = XCONS (tail)->cdr)
      {
	Lisp_Object f;

	f = XCONS (tail)->car;
	if (passed)
	  {
	    /* Decide whether this frame is eligible to be returned.  */

	    /* If we've looped all the way around without finding any
	       eligible frames, return the original frame.  */
	    if (EQ (f, frame))
	      return f;

	    /* Let minibuf decide if this frame is acceptable.  */
	    if (NILP (minibuf))
	      {
		if (! FRAME_MINIBUF_ONLY_P (XFRAME (f)))
		  return f;
	      }
	    else if (EQ (minibuf, Qvisible))
	      {
		FRAME_SAMPLE_VISIBILITY (XFRAME (f));
		if (FRAME_VISIBLE_P (XFRAME (f)))
		  return f;
	      }
	    else if (XFASTINT (minibuf) == 0)
	      {
		FRAME_SAMPLE_VISIBILITY (XFRAME (f));
		if (FRAME_VISIBLE_P (XFRAME (f))
		    || FRAME_ICONIFIED_P (XFRAME (f)))
		  return f;
	      }
	    else if (WINDOWP (minibuf))
	      {
		if (EQ (FRAME_MINIBUF_WINDOW (XFRAME (f)), minibuf)
		    /* Check that F either is, or has forwarded its focus to,
		       MINIBUF's frame.  */
		    && (EQ (WINDOW_FRAME (XWINDOW (minibuf)), f)
			|| EQ (WINDOW_FRAME (XWINDOW (minibuf)),
			       FRAME_FOCUS_FRAME (XFRAME (f)))))
		  return f;
	      }
	    else
	      return f;
	  }

	if (EQ (frame, f))
	  passed++;
      }
}

/* Return the previous frame in the frame list before FRAME.
   If MINIBUF is nil, exclude minibuffer-only frames.
   If MINIBUF is a window, include only its own frame
   and any frame now using that window as the minibuffer.
   If MINIBUF is `visible', include all visible frames.
   If MINIBUF is 0, include all visible and iconified frames.
   Otherwise, include all frames.  */

Lisp_Object
prev_frame (frame, minibuf)
     Lisp_Object frame;
     Lisp_Object minibuf;
{
  Lisp_Object tail;
  Lisp_Object prev;

  /* There must always be at least one frame in Vframe_list.  */
  if (! CONSP (Vframe_list))
    abort ();

  prev = Qnil;
  for (tail = Vframe_list; CONSP (tail); tail = XCONS (tail)->cdr)
    {
      Lisp_Object f;

      f = XCONS (tail)->car;
      if (!FRAMEP (f))
	abort ();

      if (EQ (frame, f) && !NILP (prev))
	return prev;

      /* Decide whether this frame is eligible to be returned,
	 according to minibuf.  */
      if (NILP (minibuf))
	{
	  if (! FRAME_MINIBUF_ONLY_P (XFRAME (f)))
	    prev = f;
	}
      else if (WINDOWP (minibuf))
	{
	  if (EQ (FRAME_MINIBUF_WINDOW (XFRAME (f)), minibuf)
	      /* Check that F either is, or has forwarded its focus to,
		 MINIBUF's frame.  */
	      && (EQ (WINDOW_FRAME (XWINDOW (minibuf)), f)
		  || EQ (WINDOW_FRAME (XWINDOW (minibuf)),
			 FRAME_FOCUS_FRAME (XFRAME (f)))))
	    prev = f;
	}
      else if (EQ (minibuf, Qvisible))
	{
	  FRAME_SAMPLE_VISIBILITY (XFRAME (f));
	  if (FRAME_VISIBLE_P (XFRAME (f)))
	    prev = f;
	}
      else if (XFASTINT (minibuf) == 0)
	{
	  FRAME_SAMPLE_VISIBILITY (XFRAME (f));
	  if (FRAME_VISIBLE_P (XFRAME (f))
	      || FRAME_ICONIFIED_P (XFRAME (f)))
	    prev = f;
	}
      else
	prev = f;
    }

  /* We've scanned the entire list.  */
  if (NILP (prev))
    /* We went through the whole frame list without finding a single
       acceptable frame.  Return the original frame.  */
    return frame;
  else
    /* There were no acceptable frames in the list before FRAME; otherwise,
       we would have returned directly from the loop.  Since PREV is the last
       acceptable frame in the list, return it.  */
    return prev;
}


DEFUN ("next-frame", Fnext_frame, Snext_frame, 0, 2, 0,
  "Return the next frame in the frame list after FRAME.\n\
By default, skip minibuffer-only frames.\n\
If omitted, FRAME defaults to the selected frame.\n\
If optional argument MINIFRAME is nil, exclude minibuffer-only frames.\n\
If MINIBUF is a window, include only its own frame\n\
and any frame now using that window as the minibuffer.\n\
If MINIFRAME is `visible', include all visible frames.\n\
If MINIBUF is 0, include all visible and iconified frames.\n\
Otherwise, include all frames.")
  (frame, miniframe)
     Lisp_Object frame, miniframe;
{
  Lisp_Object tail;

  if (NILP (frame))
    XSETFRAME (frame, selected_frame);
  else
    CHECK_LIVE_FRAME (frame, 0);

  return next_frame (frame, miniframe);
}

DEFUN ("previous-frame", Fprevious_frame, Sprevious_frame, 0, 2, 0,
  "Return the previous frame in the frame list before FRAME.\n\
By default, skip minibuffer-only frames.\n\
If omitted, FRAME defaults to the selected frame.\n\
If optional argument MINIFRAME is nil, exclude minibuffer-only frames.\n\
If MINIBUF is a window, include only its own frame\n\
and any frame now using that window as the minibuffer.\n\
If MINIFRAME is `visible', include all visible frames.\n\
If MINIBUF is 0, include all visible and iconified frames.\n\
Otherwise, include all frames.")
  (frame, miniframe)
     Lisp_Object frame, miniframe;
{
  Lisp_Object tail;

  if (NILP (frame))
    XSETFRAME (frame, selected_frame);
  else
    CHECK_LIVE_FRAME (frame, 0);

  return prev_frame (frame, miniframe);
}

/* Return 1 if it is ok to delete frame F;
   0 if all frames aside from F are invisible.
   (Exception: if F is the terminal frame, and we are using X, return 1.)  */

int
other_visible_frames (f)
     FRAME_PTR f;
{
  /* We know the selected frame is visible,
     so if F is some other frame, it can't be the sole visible one.  */
  if (f == selected_frame)
    {
      Lisp_Object frames;
      int count = 0;

      for (frames = Vframe_list;
	   CONSP (frames);
	   frames = XCONS (frames)->cdr)
	{
	  Lisp_Object this;

	  this = XCONS (frames)->car;
	  /* Verify that the frame's window still exists
	     and we can still talk to it.  And note any recent change
	     in visibility.  */
#ifdef HAVE_X_WINDOWS
	  if (FRAME_X_P (XFRAME (this)))
	    {
	      x_sync (XFRAME (this));
	      FRAME_SAMPLE_VISIBILITY (XFRAME (this));
	    }
#endif

	  if (FRAME_VISIBLE_P (XFRAME (this))
	      || FRAME_ICONIFIED_P (XFRAME (this))
	      /* Allow deleting the terminal frame when at least
		 one X frame exists!  */
	      || (FRAME_X_P (XFRAME (this)) && !FRAME_X_P (f)))
	    count++;
	}
      return count > 1;
    }
  return 1;
}

DEFUN ("delete-frame", Fdelete_frame, Sdelete_frame, 0, 2, "",
  "Delete FRAME, permanently eliminating it from use.\n\
If omitted, FRAME defaults to the selected frame.\n\
A frame may not be deleted if its minibuffer is used by other frames.\n\
Normally, you may not delete a frame if all other frames are invisible,\n\
but if the second optional argument FORCE is non-nil, you may do so.")
  (frame, force)
     Lisp_Object frame, force;
{
  struct frame *f;
  int minibuffer_selected;

  if (EQ (frame, Qnil))
    {
      f = selected_frame;
      XSETFRAME (frame, f);
    }
  else
    {
      CHECK_FRAME (frame, 0);
      f = XFRAME (frame);
    }

  if (! FRAME_LIVE_P (f))
    return Qnil;

  if (NILP (force) && !other_visible_frames (f))
    error ("Attempt to delete the sole visible or iconified frame");

  /* Does this frame have a minibuffer, and is it the surrogate
     minibuffer for any other frame?  */
  if (FRAME_HAS_MINIBUF_P (XFRAME (frame)))
    {
      Lisp_Object frames;

      for (frames = Vframe_list;
	   CONSP (frames);
	   frames = XCONS (frames)->cdr)
	{
	  Lisp_Object this;
	  this = XCONS (frames)->car;

	  if (! EQ (this, frame)
	      && EQ (frame,
		     WINDOW_FRAME (XWINDOW
				   (FRAME_MINIBUF_WINDOW (XFRAME (this))))))
	    error ("Attempt to delete a surrogate minibuffer frame");
	}
    }

  minibuffer_selected = EQ (minibuf_window, selected_window);

  /* Don't let the frame remain selected.  */
  if (f == selected_frame)
    do_switch_frame (next_frame (frame, Qt), Qnil, 0);

  /* Don't allow minibuf_window to remain on a deleted frame.  */
  if (EQ (f->minibuffer_window, minibuf_window))
    {
      Fset_window_buffer (selected_frame->minibuffer_window,
			  XWINDOW (minibuf_window)->buffer);
      minibuf_window = selected_frame->minibuffer_window;

      /* If the dying minibuffer window was selected,
	 select the new one.  */
      if (minibuffer_selected)
	Fselect_window (minibuf_window);
    }

  /* Clear any X selections for this frame.  */
#ifdef HAVE_X_WINDOWS
  if (FRAME_X_P (f))
    x_clear_frame_selections (f);
#endif

  /* Mark all the windows that used to be on FRAME as deleted, and then
     remove the reference to them.  */
  delete_all_subwindows (XWINDOW (f->root_window));
  f->root_window = Qnil;

  Vframe_list = Fdelq (frame, Vframe_list);
  FRAME_SET_VISIBLE (f, 0);

  if (f->namebuf)
    free (f->namebuf);
  if (FRAME_CURRENT_GLYPHS (f))
    free_frame_glyphs (f, FRAME_CURRENT_GLYPHS (f));
  if (FRAME_DESIRED_GLYPHS (f))
    free_frame_glyphs (f, FRAME_DESIRED_GLYPHS (f));
  if (FRAME_TEMP_GLYPHS (f))
    free_frame_glyphs (f, FRAME_TEMP_GLYPHS (f));
  if (FRAME_INSERT_COST (f))
    free (FRAME_INSERT_COST (f));
  if (FRAME_DELETEN_COST (f))
    free (FRAME_DELETEN_COST (f));
  if (FRAME_INSERTN_COST (f))
    free (FRAME_INSERTN_COST (f));
  if (FRAME_DELETE_COST (f))
    free (FRAME_DELETE_COST (f));

  /* Since some events are handled at the interrupt level, we may get
     an event for f at any time; if we zero out the frame's display
     now, then we may trip up the event-handling code.  Instead, we'll
     promise that the display of the frame must be valid until we have
     called the window-system-dependent frame destruction routine.  */