xfns.c

/* Functions for the X window system.
   Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
                 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
                 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>
#include <stdio.h>
#include <math.h>
#include <setjmp.h>
#include <ctype.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

/* This makes the fields of a Display accessible, in Xlib header files.  */

#define XLIB_ILLEGAL_ACCESS

#include "lisp.h"
#include "xterm.h"
#include "frame.h"
#include "window.h"
#include "buffer.h"
#include "intervals.h"
#include "dispextern.h"
#include "keyboard.h"
#include "blockinput.h"
#include <epaths.h>
#include "character.h"
#include "charset.h"
#include "coding.h"
#include "fontset.h"
#include "systime.h"
#include "termhooks.h"
#include "atimer.h"
#include "termchar.h"
#include "font.h"

#ifdef HAVE_X_WINDOWS

#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>

#if 1 /* Used to be #ifdef EMACS_BITMAP_FILES, but this should always work.  */
#include "bitmaps/gray.xbm"
#else
#include <X11/bitmaps/gray>
#endif

#include "xsettings.h"

#ifdef USE_GTK
#include "gtkutil.h"
#endif

#ifdef USE_X_TOOLKIT
#include <X11/Shell.h>

#ifndef USE_MOTIF
#ifdef HAVE_XAW3D
#include <X11/Xaw3d/Paned.h>
#include <X11/Xaw3d/Label.h>
#else /* !HAVE_XAW3D */
#include <X11/Xaw/Paned.h>
#include <X11/Xaw/Label.h>
#endif /* HAVE_XAW3D */
#endif /* USE_MOTIF */

#ifdef USG
#undef USG	/* ####KLUDGE for Solaris 2.2 and up */
#include <X11/Xos.h>
#define USG
#else
#include <X11/Xos.h>
#endif

#include "widget.h"

#include "../lwlib/lwlib.h"

#ifdef USE_MOTIF
#include <Xm/Xm.h>
#include <Xm/DialogS.h>
#include <Xm/FileSB.h>
#endif

#if !defined(NO_EDITRES)
#define HACK_EDITRES
extern void _XEditResCheckMessages ();
#endif /* not defined NO_EDITRES */

/* Unique id counter for widgets created by the Lucid Widget Library.  */

extern LWLIB_ID widget_id_tick;

#ifdef USE_LUCID
/* This is part of a kludge--see lwlib/xlwmenu.c.  */
extern XFontStruct *xlwmenu_default_font;
#endif

extern void free_frame_menubar ();
extern double atof ();

#ifdef USE_MOTIF

/* LessTif/Motif version info.  */

static Lisp_Object Vmotif_version_string;

#endif /* USE_MOTIF */

#endif /* USE_X_TOOLKIT */

#ifdef USE_GTK

/* GTK+ version info */

static Lisp_Object Vgtk_version_string;

#endif /* USE_GTK */

#define MAXREQUEST(dpy) (XMaxRequestSize (dpy))

/* The gray bitmap `bitmaps/gray'.  This is done because xterm.c uses
   it, and including `bitmaps/gray' more than once is a problem when
   config.h defines `static' as an empty replacement string.  */

int gray_bitmap_width = gray_width;
int gray_bitmap_height = gray_height;
char *gray_bitmap_bits = gray_bits;

/* Non-zero means prompt with the old GTK file selection dialog.  */

int x_gtk_use_old_file_dialog;

/* If non-zero, by default show hidden files in the GTK file chooser.  */

int x_gtk_show_hidden_files;

/* If non-zero, don't show additional help text in the GTK file chooser.  */

int x_gtk_file_dialog_help_text;

/* If non-zero, don't collapse to tool bar when it is detached.  */

int x_gtk_whole_detached_tool_bar;

/* The background and shape of the mouse pointer, and shape when not
   over text or in the modeline.  */

Lisp_Object Vx_pointer_shape, Vx_nontext_pointer_shape, Vx_mode_pointer_shape;
Lisp_Object Vx_hourglass_pointer_shape;

/* The shape when over mouse-sensitive text.  */

Lisp_Object Vx_sensitive_text_pointer_shape;

/* If non-nil, the pointer shape to indicate that windows can be
   dragged horizontally.  */

Lisp_Object Vx_window_horizontal_drag_shape;

/* Color of chars displayed in cursor box.  */

Lisp_Object Vx_cursor_fore_pixel;

/* Nonzero if using X.  */

static int x_in_use;

/* Non nil if no window manager is in use.  */

Lisp_Object Vx_no_window_manager;

/* Regexp matching a font name whose width is the same as `PIXEL_SIZE'.  */

Lisp_Object Vx_pixel_size_width_font_regexp;

Lisp_Object Qnone;
Lisp_Object Qsuppress_icon;
Lisp_Object Qundefined_color;
Lisp_Object Qcompound_text, Qcancel_timer;
Lisp_Object Qfont_param;

/* In dispnew.c */

extern Lisp_Object Vwindow_system_version;

/* The below are defined in frame.c.  */

extern Lisp_Object Qtooltip;

#if GLYPH_DEBUG
int image_cache_refcount, dpyinfo_refcount;
#endif

#if defined (USE_GTK) && defined (HAVE_FREETYPE)
char *x_last_font_name;
#endif


/* Error if we are not connected to X.  */

void
check_x ()
{
  if (! x_in_use)
    error ("X windows are not in use or not initialized");
}

/* Nonzero if we can use mouse menus.
   You should not call this unless HAVE_MENUS is defined.  */

int
have_menus_p ()
{
  return x_in_use;
}

/* Extract a frame as a FRAME_PTR, defaulting to the selected frame
   and checking validity for X.  */

FRAME_PTR
check_x_frame (frame)
     Lisp_Object frame;
{
  FRAME_PTR f;

  if (NILP (frame))
    frame = selected_frame;
  CHECK_LIVE_FRAME (frame);
  f = XFRAME (frame);
  if (! FRAME_X_P (f))
    error ("Non-X frame used");
  return f;
}

/* Let the user specify an X display with a Lisp object.
   OBJECT may be nil, a frame or a terminal object.
   nil stands for the selected frame--or, if that is not an X frame,
   the first X display on the list.  */

struct x_display_info *
check_x_display_info (object)
     Lisp_Object object;
{
  struct x_display_info *dpyinfo = NULL;

  if (NILP (object))
    {
      struct frame *sf = XFRAME (selected_frame);

      if (FRAME_X_P (sf) && FRAME_LIVE_P (sf))
	dpyinfo = FRAME_X_DISPLAY_INFO (sf);
      else if (x_display_list != 0)
	dpyinfo = x_display_list;
      else
	error ("X windows are not in use or not initialized");
    }
  else if (TERMINALP (object))
    {
      struct terminal *t = get_terminal (object, 1);

      if (t->type != output_x_window)
        error ("Terminal %d is not an X display", XINT (object));

      dpyinfo = t->display_info.x;
    }
  else if (STRINGP (object))
    dpyinfo = x_display_info_for_name (object);
  else
    {
      FRAME_PTR f = check_x_frame (object);
      dpyinfo = FRAME_X_DISPLAY_INFO (f);
    }

  return dpyinfo;
}


/* Return the Emacs frame-object corresponding to an X window.
   It could be the frame's main window or an icon window.  */

/* This function can be called during GC, so use GC_xxx type test macros.  */

struct frame *
x_window_to_frame (dpyinfo, wdesc)
     struct x_display_info *dpyinfo;
     int wdesc;
{
  Lisp_Object tail, frame;
  struct frame *f;

  if (wdesc == None) return 0;

  for (tail = Vframe_list; CONSP (tail); tail = XCDR (tail))
    {
      frame = XCAR (tail);
      if (!FRAMEP (frame))
        continue;
      f = XFRAME (frame);
      if (!FRAME_X_P (f) || FRAME_X_DISPLAY_INFO (f) != dpyinfo)
	continue;
      if (f->output_data.x->hourglass_window == wdesc)
	return f;
#ifdef USE_X_TOOLKIT
      if ((f->output_data.x->edit_widget
	   && XtWindow (f->output_data.x->edit_widget) == wdesc)
	  /* A tooltip frame?  */
	  || (!f->output_data.x->edit_widget
	      && FRAME_X_WINDOW (f) == wdesc)
          || f->output_data.x->icon_desc == wdesc)
        return f;
#else /* not USE_X_TOOLKIT */
#ifdef USE_GTK
      if (f->output_data.x->edit_widget)
      {
        GtkWidget *gwdesc = xg_win_to_widget (dpyinfo->display, wdesc);
        struct x_output *x = f->output_data.x;
        if (gwdesc != 0 && gwdesc == x->edit_widget)
          return f;
      }
#endif /* USE_GTK */
      if (FRAME_X_WINDOW (f) == wdesc
          || f->output_data.x->icon_desc == wdesc)
        return f;
#endif /* not USE_X_TOOLKIT */
    }
  return 0;
}

#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
/* Like x_window_to_frame but also compares the window with the widget's
   windows.  */

struct frame *
x_any_window_to_frame (dpyinfo, wdesc)
     struct x_display_info *dpyinfo;
     int wdesc;
{
  Lisp_Object tail, frame;
  struct frame *f, *found;
  struct x_output *x;

  if (wdesc == None) return NULL;

  found = NULL;
  for (tail = Vframe_list; CONSP (tail) && !found; tail = XCDR (tail))
    {
      frame = XCAR (tail);
      if (!FRAMEP (frame))
        continue;

      f = XFRAME (frame);
      if (FRAME_X_P (f) && FRAME_X_DISPLAY_INFO (f) == dpyinfo)
	{
	  /* This frame matches if the window is any of its widgets.  */
	  x = f->output_data.x;
	  if (x->hourglass_window == wdesc)
	    found = f;
	  else if (x->widget)
	    {
#ifdef USE_GTK
              GtkWidget *gwdesc = xg_win_to_widget (dpyinfo->display, wdesc);
              if (gwdesc != 0
                  && gtk_widget_get_toplevel (gwdesc) == x->widget)
                found = f;
#else
	      if (wdesc == XtWindow (x->widget)
		  || wdesc == XtWindow (x->column_widget)
		  || wdesc == XtWindow (x->edit_widget))
		found = f;
	      /* Match if the window is this frame's menubar.  */
	      else if (lw_window_is_in_menubar (wdesc, x->menubar_widget))
		found = f;
#endif
	    }
	  else if (FRAME_X_WINDOW (f) == wdesc)
	    /* A tooltip frame.  */
	    found = f;
	}
    }

  return found;
}

/* Likewise, but consider only the menu bar widget.  */

struct frame *
x_menubar_window_to_frame (dpyinfo, event)
     struct x_display_info *dpyinfo;
     XEvent *event;
{
  Window wdesc = event->xany.window;
  Lisp_Object tail, frame;
  struct frame *f;
  struct x_output *x;

  if (wdesc == None) return 0;

  for (tail = Vframe_list; CONSP (tail); tail = XCDR (tail))
    {
      frame = XCAR (tail);
      if (!FRAMEP (frame))
        continue;
      f = XFRAME (frame);
      if (!FRAME_X_P (f) || FRAME_X_DISPLAY_INFO (f) != dpyinfo)
	continue;
      x = f->output_data.x;
#ifdef USE_GTK
      if (x->menubar_widget && xg_event_is_for_menubar (f, event))
        return f;
#else
      /* Match if the window is this frame's menubar.  */
      if (x->menubar_widget
	  && lw_window_is_in_menubar (wdesc, x->menubar_widget))
	return f;
#endif
    }
  return 0;
}

/* Return the frame whose principal (outermost) window is WDESC.
   If WDESC is some other (smaller) window, we return 0.  */

struct frame *
x_top_window_to_frame (dpyinfo, wdesc)
     struct x_display_info *dpyinfo;
     int wdesc;
{
  Lisp_Object tail, frame;
  struct frame *f;
  struct x_output *x;

  if (wdesc == None) return 0;

  for (tail = Vframe_list; CONSP (tail); tail = XCDR (tail))
    {
      frame = XCAR (tail);
      if (!FRAMEP (frame))
        continue;
      f = XFRAME (frame);
      if (!FRAME_X_P (f) || FRAME_X_DISPLAY_INFO (f) != dpyinfo)
	continue;
      x = f->output_data.x;

      if (x->widget)
	{
	  /* This frame matches if the window is its topmost widget.  */
#ifdef USE_GTK
          GtkWidget *gwdesc = xg_win_to_widget (dpyinfo->display, wdesc);
          if (gwdesc == x->widget)
            return f;
#else
	  if (wdesc == XtWindow (x->widget))
	    return f;
#if 0 /* I don't know why it did this,
	 but it seems logically wrong,
	 and it causes trouble for MapNotify events.  */
	  /* Match if the window is this frame's menubar.  */
	  if (x->menubar_widget
	      && wdesc == XtWindow (x->menubar_widget))
	    return f;
#endif
#endif
	}
      else if (FRAME_X_WINDOW (f) == wdesc)
	/* Tooltip frame.  */
	return f;
    }
  return 0;
}
#endif /* USE_X_TOOLKIT || USE_GTK */



static void x_default_font_parameter P_ ((struct frame *, Lisp_Object));

static Lisp_Object unwind_create_frame P_ ((Lisp_Object));
static Lisp_Object unwind_create_tip_frame P_ ((Lisp_Object));

void x_set_foreground_color P_ ((struct frame *, Lisp_Object, Lisp_Object));
static void x_set_wait_for_wm P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_set_background_color P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_set_mouse_color P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_set_cursor_color P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_set_border_color P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_set_cursor_type P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_set_icon_type P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_set_icon_name P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_explicitly_set_name P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_set_menu_bar_lines P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_set_title P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_set_tool_bar_lines P_ ((struct frame *, Lisp_Object, Lisp_Object));
void x_set_scroll_bar_foreground P_ ((struct frame *, Lisp_Object,
				      Lisp_Object));
void x_set_scroll_bar_background P_ ((struct frame *, Lisp_Object,
				      Lisp_Object));
static Lisp_Object x_default_scroll_bar_color_parameter P_ ((struct frame *,
							     Lisp_Object,
							     Lisp_Object,
							     char *, char *,
							     int));


/* Store the screen positions of frame F into XPTR and YPTR.
   These are the positions of the containing window manager window,
   not Emacs's own window.  */

void
x_real_positions (f, xptr, yptr)
     FRAME_PTR f;
     int *xptr, *yptr;
{
  int win_x, win_y, outer_x, outer_y;
  int real_x = 0, real_y = 0;
  int had_errors = 0;
  Window win = f->output_data.x->parent_desc;
  Atom actual_type;
  unsigned long actual_size, bytes_remaining;
  int i, rc, actual_format;
  struct x_display_info *dpyinfo = FRAME_X_DISPLAY_INFO (f);
  long max_len = 400;
  Display *dpy = FRAME_X_DISPLAY (f);
  unsigned char *tmp_data = NULL;
  Atom target_type = XA_CARDINAL;

  BLOCK_INPUT;

  x_catch_errors (dpy);

  if (win == dpyinfo->root_window)
    win = FRAME_OUTER_WINDOW (f);

  /* This loop traverses up the containment tree until we hit the root
     window.  Window managers may intersect many windows between our window
     and the root window.  The window we find just before the root window
     should be the outer WM window. */
  for (;;)
    {
      Window wm_window, rootw;
      Window *tmp_children;
      unsigned int tmp_nchildren;
      int success;

      success = XQueryTree (FRAME_X_DISPLAY (f), win, &rootw,
			    &wm_window, &tmp_children, &tmp_nchildren);

      had_errors = x_had_errors_p (FRAME_X_DISPLAY (f));

      /* Don't free tmp_children if XQueryTree failed.  */
      if (! success)
	break;

      XFree ((char *) tmp_children);

      if (wm_window == rootw || had_errors)
        break;

      win = wm_window;
    }

  if (! had_errors)
    {
      unsigned int ign;
      Window child, rootw;

      /* Get the real coordinates for the WM window upper left corner */
      XGetGeometry (FRAME_X_DISPLAY (f), win,
                    &rootw, &real_x, &real_y, &ign, &ign, &ign, &ign);

      /* Translate real coordinates to coordinates relative to our
         window.  For our window, the upper left corner is 0, 0.
         Since the upper left corner of the WM window is outside
         our window, win_x and win_y will be negative:

         ------------------          ---> x
         |      title                |
         | -----------------         v y
         | |  our window
      */
      XTranslateCoordinates (FRAME_X_DISPLAY (f),

			     /* From-window, to-window.  */
			     FRAME_X_DISPLAY_INFO (f)->root_window,
                             FRAME_X_WINDOW (f),

			     /* From-position, to-position.  */
                             real_x, real_y, &win_x, &win_y,

			     /* Child of win.  */
			     &child);

      if (FRAME_X_WINDOW (f) == FRAME_OUTER_WINDOW (f))
	{
          outer_x = win_x;
          outer_y = win_y;
	}
      else
        {
          XTranslateCoordinates (FRAME_X_DISPLAY (f),

                                 /* From-window, to-window.  */
                                 FRAME_X_DISPLAY_INFO (f)->root_window,
                                 FRAME_OUTER_WINDOW (f),

                                 /* From-position, to-position.  */
                                 real_x, real_y, &outer_x, &outer_y,

                                 /* Child of win.  */
                                 &child);
	}

      had_errors = x_had_errors_p (FRAME_X_DISPLAY (f));
    }


  if (dpyinfo->root_window == f->output_data.x->parent_desc)
    {
      /* Try _NET_FRAME_EXTENTS if our parent is the root window.  */
      rc = XGetWindowProperty (dpy, win, dpyinfo->Xatom_net_frame_extents,
                               0, max_len, False, target_type,
                               &actual_type, &actual_format, &actual_size,
                               &bytes_remaining, &tmp_data);

      if (rc == Success && actual_type == target_type && !x_had_errors_p (dpy)
          && actual_size == 4 && actual_format == 32)
        {
          int ign;
          Window rootw;

          XGetGeometry (FRAME_X_DISPLAY (f), win,
                        &rootw, &real_x, &real_y, &ign, &ign, &ign, &ign);
          long *fe = (long *)tmp_data;
      
          outer_x = -fe[0];
          outer_y = -fe[2];
          real_x -= fe[0];
          real_y -= fe[2];
        }
    }

  if (tmp_data) XFree (tmp_data);

  x_uncatch_errors ();

  UNBLOCK_INPUT;

  if (had_errors) return;

  f->x_pixels_diff = -win_x;
  f->y_pixels_diff = -win_y;

  FRAME_X_OUTPUT (f)->x_pixels_outer_diff = -outer_x;
  FRAME_X_OUTPUT (f)->y_pixels_outer_diff = -outer_y;

  *xptr = real_x;
  *yptr = real_y;
}




/* Gamma-correct COLOR on frame F.  */

void
gamma_correct (f, color)
     struct frame *f;
     XColor *color;
{
  if (f->gamma)
    {
      color->red = pow (color->red / 65535.0, f->gamma) * 65535.0 + 0.5;
      color->green = pow (color->green / 65535.0, f->gamma) * 65535.0 + 0.5;
      color->blue = pow (color->blue / 65535.0, f->gamma) * 65535.0 + 0.5;
    }
}


/* Decide if color named COLOR_NAME is valid for use on frame F.  If
   so, return the RGB values in COLOR.  If ALLOC_P is non-zero,
   allocate the color.  Value is zero if COLOR_NAME is invalid, or
   no color could be allocated.  */

int
x_defined_color (f, color_name, color, alloc_p)
     struct frame *f;
     char *color_name;
     XColor *color;
     int alloc_p;
{
  int success_p;
  Display *dpy = FRAME_X_DISPLAY (f);
  Colormap cmap = FRAME_X_COLORMAP (f);

  BLOCK_INPUT;
  success_p = XParseColor (dpy, cmap, color_name, color);
  if (success_p && alloc_p)
    success_p = x_alloc_nearest_color (f, cmap, color);
  UNBLOCK_INPUT;

  return success_p;
}


/* Return the pixel color value for color COLOR_NAME on frame F.  If F
   is a monochrome frame, return MONO_COLOR regardless of what ARG says.
   Signal an error if color can't be allocated.  */

int
x_decode_color (f, color_name, mono_color)
     FRAME_PTR f;
     Lisp_Object color_name;
     int mono_color;
{
  XColor cdef;

  CHECK_STRING (color_name);

#if 0 /* Don't do this.  It's wrong when we're not using the default
	 colormap, it makes freeing difficult, and it's probably not
	 an important optimization.  */
  if (strcmp (SDATA (color_name), "black") == 0)
    return BLACK_PIX_DEFAULT (f);
  else if (strcmp (SDATA (color_name), "white") == 0)
    return WHITE_PIX_DEFAULT (f);
#endif

  /* Return MONO_COLOR for monochrome frames.  */
  if (FRAME_X_DISPLAY_INFO (f)->n_planes == 1)
    return mono_color;

  /* x_defined_color is responsible for coping with failures
     by looking for a near-miss.  */
  if (x_defined_color (f, SDATA (color_name), &cdef, 1))
    return cdef.pixel;

  signal_error ("Undefined color", color_name);
}



/* Change the `wait-for-wm' frame parameter of frame F.  OLD_VALUE is
   the previous value of that parameter, NEW_VALUE is the new value.
   See also the comment of wait_for_wm in struct x_output.  */

static void
x_set_wait_for_wm (f, new_value, old_value)
     struct frame *f;
     Lisp_Object new_value, old_value;
{
  f->output_data.x->wait_for_wm = !NILP (new_value);
}

#ifdef USE_GTK

/* Set icon from FILE for frame F.  By using GTK functions the icon
   may be any format that GdkPixbuf knows about, i.e. not just bitmaps.  */

int
xg_set_icon (f, file)
    FRAME_PTR f;
    Lisp_Object file;
{
  int result = 0;
  Lisp_Object found;

  found = x_find_image_file (file);

  if (! NILP (found))
    {
      GdkPixbuf *pixbuf;
      GError *err = NULL;
      char *filename = (char *) SDATA (found);
      BLOCK_INPUT;

      pixbuf = gdk_pixbuf_new_from_file (filename, &err);

      if (pixbuf)
	{
	  gtk_window_set_icon (GTK_WINDOW (FRAME_GTK_OUTER_WIDGET (f)),
			       pixbuf);
	  g_object_unref (pixbuf);

	  result = 1;
	}
      else
	g_error_free (err);

      UNBLOCK_INPUT;
    }

  return result;
}

int
xg_set_icon_from_xpm_data (f, data)
    FRAME_PTR f;
    char **data;
{
  int result = 0;
  GdkPixbuf *pixbuf = gdk_pixbuf_new_from_xpm_data ((const char **) data);

  if (!pixbuf)
    return 0;

  gtk_window_set_icon (GTK_WINDOW (FRAME_GTK_OUTER_WIDGET (f)), pixbuf);
  g_object_unref (pixbuf);
  return 1;
}
#endif /* USE_GTK */


/* Functions called only from `x_set_frame_param'
   to set individual parameters.

   If FRAME_X_WINDOW (f) is 0,
   the frame is being created and its X-window does not exist yet.
   In that case, just record the parameter's new value
   in the standard place; do not attempt to change the window.  */

void
x_set_foreground_color (f, arg, oldval)
     struct frame *f;
     Lisp_Object arg, oldval;
{
  struct x_output *x = f->output_data.x;
  unsigned long fg, old_fg;

  fg = x_decode_color (f, arg, BLACK_PIX_DEFAULT (f));
  old_fg = FRAME_FOREGROUND_PIXEL (f);
  FRAME_FOREGROUND_PIXEL (f) = fg;

  if (FRAME_X_WINDOW (f) != 0)
    {
      Display *dpy = FRAME_X_DISPLAY (f);

      BLOCK_INPUT;
      XSetForeground (dpy, x->normal_gc, fg);
      XSetBackground (dpy, x->reverse_gc, fg);

      if (x->cursor_pixel == old_fg)
	{
	  unload_color (f, x->cursor_pixel);
	  x->cursor_pixel = x_copy_color (f, fg);
	  XSetBackground (dpy, x->cursor_gc, x->cursor_pixel);
	}