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Last active January 28, 2024 12:59
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Simple app to toggle window decorations.
* Copyright (C) 2017 Alberts Muktupāvels
* This program 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.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <>.
* Compile with:
* gcc toggle-decorations.c -Wall -o toggle-decorations `pkg-config --cflags --libs x11`
* Usage:
* toggle-decorations 0x1234567
* Support me:
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <X11/Xlib.h>
typedef struct
unsigned long flags;
unsigned long functions;
unsigned long decorations;
long input_mode;
unsigned long status;
} MotifWmHints;
static MotifWmHints *
get_motif_wm_hints (Display *display,
Window window)
Atom property;
int result;
Atom actual_type;
int actual_format;
unsigned long nitems;
unsigned long bytes_after;
unsigned char *data;
property = XInternAtom (display, "_MOTIF_WM_HINTS", False);
result = XGetWindowProperty (display, window, property,
0, LONG_MAX, False, AnyPropertyType,
&actual_type, &actual_format,
&nitems, &bytes_after, &data);
if (result == Success && data != NULL)
size_t data_size;
size_t max_size;
MotifWmHints *hints;
data_size = nitems * sizeof (long);
max_size = sizeof (*hints);
hints = calloc (1, max_size);
memcpy (hints, data, data_size > max_size ? max_size : data_size);
XFree (data);
return hints;
return NULL;
static void
toggle_window_decorations (Display *display,
Window window)
MotifWmHints *hints;
Atom property;
int nelements;
hints = get_motif_wm_hints (display, window);
if (hints == NULL)
hints = calloc (1, sizeof (*hints));
hints->decorations = (1L << 0);
hints->flags |= (1L << 1);
hints->decorations = hints->decorations == 0 ? (1L << 0) : 0;
property = XInternAtom (display, "_MOTIF_WM_HINTS", False);
nelements = sizeof (*hints) / sizeof (long);
XChangeProperty (display, window, property, property, 32, PropModeReplace,
(unsigned char *) hints, nelements);
free (hints);
main (int argc,
char *argv[])
Display *display;
Window window;
display = XOpenDisplay (NULL);
if (display == NULL)
return 1;
window = 0;
if (argc > 1)
sscanf (argv[1], "0x%lx", &window);
if (window == 0)
sscanf (argv[1], "%lu", &window);
if (window == 0)
return 1;
toggle_window_decorations (display, window);
XCloseDisplay (display);
return 0;
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Quickly looked at your fork. In remove_take_focus_protocol you want Atom new_list[count + 1]; or Atom new_list[count + (bAdd ? 1 : 0)]; to make sure new_list has space for extra Atom.

cool thx!! fixed there :)

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rysson commented Jul 17, 2021

It's very useful, thanks.

argc is (almost) always grater than zero ([0] is the program name).

I suggest to change L119 to (it fixes crash):

  if (argc > 1)

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@rysson Thanks for suggestion!

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