➤ dget --extract --allow-unauthenticated https://launchpad.net/ubuntu/+archive/primary/+sourcefiles/gtk3-nocsd/3-1ubuntu3/gtk3-nocsd_3-1ubuntu3.dsc
dget: retrieving https://launchpad.net/ubuntu/+archive/primary/+sourcefiles/gtk3-nocsd/3-1ubuntu3/gtk3-nocsd_3-1ubuntu3.dsc
...
dpkg-source: info: extracting gtk3-nocsd in gtk3-nocsd-3
dpkg-source: info: unpacking gtk3-nocsd_3.orig.tar.gz
dpkg-source: info: unpacking gtk3-nocsd_3-1ubuntu3.debian.tar.xz
dpkg-source: info: using patch list from debian/patches/series
dpkg-source: info: applying debian-specifics-in-manpage.patch
dpkg-source: info: applying add-gtk4-support.patch

➤ ls -1
gtk3-nocsd-3
gtk3-nocsd_3-1ubuntu3.debian.tar.xz
gtk3-nocsd_3-1ubuntu3.dsc
gtk3-nocsd_3.orig.tar.gz

➤ ls -1 gtk3-nocsd-3/debian/patches
add-gtk4-support.patch
debian-specifics-in-manpage.patch
series

➤ cat gtk3-nocsd-3/debian/patches/add-gtk4-support.patch
Description: add some description: Add Gtk4 Support
Imported new upstream version 4 and fixed logic error in gtk_window_set_titlebar
Imported from https://github.com/ZaWertun/gtk3-nocsd
Author: Brett Bogert <bbogert24@gmail.com>
Bug: https://bugs.launchpad.net/ubuntu/+source/gtk3-nocsd/+bug/1946161
--- a/gtk3-nocsd.c
+++ b/gtk3-nocsd.c
@@ -22,6 +22,7 @@
 
 #define _GNU_SOURCE
 #include <dlfcn.h>
+#include <link.h>
 #include <unistd.h>
 #include <string.h>
 #include <stdlib.h>
@@ -38,6 +39,16 @@
 
 #include <gobject/gvaluecollector.h>
 
+#ifdef __FreeBSD__
+#include <sys/elf_generic.h>
+#define ElfW(t) Elf##_##t
+#endif
+
+#ifdef G_TYPE_INSTANCE_GET_PRIVATE
+#   undef G_TYPE_INSTANCE_GET_PRIVATE
+#endif
+#define G_TYPE_INSTANCE_GET_PRIVATE(instance, g_type, c_type)   ((c_type*) g_type_instance_get_private ((GTypeInstance*) (instance),(g_type)))
+
 typedef void (*gtk_window_buildable_add_child_t) (GtkBuildable *buildable, GtkBuilder *builder, GObject *child, const gchar *type);
 typedef GObject* (*gtk_dialog_constructor_t) (GType type, guint n_construct_properties, GObjectConstructParam *construct_params);
 typedef char *(*gtk_check_version_t) (guint required_major, guint required_minor, guint required_micro);
@@ -111,12 +122,17 @@ static void * volatile library_handles[N
 static pthread_key_t key_tls;
 static pthread_once_t key_tls_once = PTHREAD_ONCE_INIT;
 
+/* Marking both as volatile here saves the trouble of caring about
+ * memory barriers. */
+static volatile gboolean is_compatible_gtk_version_cached = FALSE;
+static volatile gboolean is_compatible_gtk_version_checked = FALSE;
+static volatile int gtk2_active;
+
 typedef struct gtk3_nocsd_tls_data_t {
   // When set to true, this override gdk_screen_is_composited() and let it
   // return FALSE temporarily. Then, client-side decoration (CSD) cannot be initialized.
   volatile int disable_composite;
   volatile int signal_capture_handler;
-  volatile int fake_global_decoration_layout;
   volatile int in_info_collect;
   const char *volatile  signal_capture_name;
   volatile gpointer signal_capture_instance;
@@ -140,6 +156,12 @@ static void *find_orig_function(int try_
     void *handle;
     void *symptr;
 
+    /* Ok, so in case both gtk2 + gtk3 are loaded, but we are using
+     * gtk2, we don't know what RTLD_NEXT is going to choose - so we
+     * must explicitly pick up the gtk2 versions... */
+    if (try_gtk2 && gtk2_active)
+        goto try_gtk2_version;
+
     /* This will work in most cases, and is completely thread-safe. */
     handle = dlsym(RTLD_NEXT, symbol);
     if (handle)
@@ -248,10 +270,12 @@ RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY,
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_header_bar_set_show_close_button, void, (GtkHeaderBar *bar, gboolean setting), (bar, setting))
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_header_bar_set_decoration_layout, void, (GtkHeaderBar *bar, const gchar *layout), (bar, layout))
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_header_bar_get_decoration_layout, const gchar *, (GtkHeaderBar *bar), (bar))
+RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_header_bar_get_custom_title, GtkWidget *, (GtkHeaderBar *bar), (bar))
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_style_context_add_class, void, (GtkStyleContext *context, const gchar *class_name), (context, class_name))
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_style_context_remove_class, void, (GtkStyleContext *context, const gchar *class_name), (context, class_name))
-RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_style_context_add_provider, void, (GtkStyleContext *context, GtkStyleProvider *provider, guint priority), (context, provider, priority))
+RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_style_context_add_provider_for_screen, void, (GdkScreen *screen, GtkStyleProvider *provider, guint priority), (screen, provider, priority))
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_style_provider_get_type, GType, (), ())
+RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_widget_hide, void, (GtkWidget *widget), (widget))
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_widget_destroy, void, (GtkWidget *widget), (widget))
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_widget_get_mapped, gboolean, (GtkWidget *widget), (widget))
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_widget_get_realized, gboolean, (GtkWidget *widget), (widget))
@@ -262,6 +286,7 @@ RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY,
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_widget_realize, void, (GtkWidget *widget), (widget))
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_widget_get_settings, GtkSettings *, (GtkWidget *widget), (widget))
 RUNTIME_IMPORT_FUNCTION(0, GTK_LIBRARY, gtk_widget_get_toplevel, GtkWidget *, (GtkWidget *widget), (widget))
+RUNTIME_IMPORT_FUNCTION(0, GDK_LIBRARY, gdk_screen_get_default, GdkScreen *, (), ())
 RUNTIME_IMPORT_FUNCTION(0, GDK_LIBRARY, gdk_window_get_user_data, void, (GdkWindow *window, gpointer *data), (window, data))
 RUNTIME_IMPORT_FUNCTION(1, GDK_LIBRARY, gdk_screen_is_composited, gboolean, (GdkScreen *screen), (screen))
 RUNTIME_IMPORT_FUNCTION(1, GDK_LIBRARY, gdk_window_set_decorations, void, (GdkWindow *window, GdkWMDecoration decorations), (window, decorations))
@@ -287,6 +312,7 @@ RUNTIME_IMPORT_FUNCTION(0, GOBJECT_LIBRA
 RUNTIME_IMPORT_FUNCTION(0, GOBJECT_LIBRARY, g_value_unset, void, (GValue *value), (value))
 RUNTIME_IMPORT_FUNCTION(0, GOBJECT_LIBRARY, g_value_get_string, const gchar *, (const GValue *value), (value))
 RUNTIME_IMPORT_FUNCTION(0, GOBJECT_LIBRARY, g_value_get_boolean, gboolean, (const GValue *value), (value))
+RUNTIME_IMPORT_FUNCTION(0, GOBJECT_LIBRARY, g_type_name, const gchar *, (GType type), (type))
 RUNTIME_IMPORT_FUNCTION(0, GLIB_LIBRARY, g_getenv, gchar *, (const char *name), (name))
 RUNTIME_IMPORT_FUNCTION(0, GLIB_LIBRARY, g_logv, void, (const gchar *log_domain, GLogLevelFlags log_level, const gchar *format, va_list args), (log_domain, log_level, format, args))
 RUNTIME_IMPORT_FUNCTION(0, GLIB_LIBRARY, g_free, void, (gpointer mem), (mem))
@@ -314,10 +340,12 @@ RUNTIME_IMPORT_FUNCTION(0, GIREPOSITORY_
 #define orig_gtk_header_bar_set_show_close_button        rtlookup_gtk_header_bar_set_show_close_button
 #define orig_gtk_header_bar_set_decoration_layout        rtlookup_gtk_header_bar_set_decoration_layout
 #define orig_gtk_header_bar_get_decoration_layout        rtlookup_gtk_header_bar_get_decoration_layout
+#define gtk_header_bar_get_custom_title                  rtlookup_gtk_header_bar_get_custom_title
 #define gtk_style_context_add_class                      rtlookup_gtk_style_context_add_class
 #define gtk_style_context_remove_class                   rtlookup_gtk_style_context_remove_class
-#define gtk_style_context_add_provider                   rtlookup_gtk_style_context_add_provider
+#define gtk_style_context_add_provider_for_screen        rtlookup_gtk_style_context_add_provider_for_screen
 #define gtk_style_provider_get_type                      rtlookup_gtk_style_provider_get_type
+#define gtk_widget_hide                                  rtlookup_gtk_widget_hide
 #define gtk_widget_destroy                               rtlookup_gtk_widget_destroy
 #define gtk_widget_get_mapped                            rtlookup_gtk_widget_get_mapped
 #define gtk_widget_get_realized                          rtlookup_gtk_widget_get_realized
@@ -326,9 +354,11 @@ RUNTIME_IMPORT_FUNCTION(0, GIREPOSITORY_
 #define gtk_widget_set_parent                            rtlookup_gtk_widget_set_parent
 #define gtk_widget_unrealize                             rtlookup_gtk_widget_unrealize
 #define gtk_widget_realize                               rtlookup_gtk_widget_realize
+#define gdk_screen_get_default                           rtlookup_gdk_screen_get_default
 #define gdk_window_get_user_data                         rtlookup_gdk_window_get_user_data
 #define orig_gdk_screen_is_composited                    rtlookup_gdk_screen_is_composited
 #define orig_gdk_window_set_decorations                  rtlookup_gdk_window_set_decorations
+#define g_list_free                                      rtlookup_g_list_free
 #define g_object_get_data                                rtlookup_g_object_get_data
 #define g_object_set_data                                rtlookup_g_object_set_data
 #define g_type_check_class_cast                          rtlookup_g_type_check_class_cast
@@ -337,12 +367,16 @@ RUNTIME_IMPORT_FUNCTION(0, GIREPOSITORY_
 #define g_object_class_find_property                     rtlookup_g_object_class_find_property
 #define g_object_get_valist                              rtlookup_g_object_get_valist
 #define g_object_get_property                            rtlookup_g_object_get_property
+#ifdef g_object_ref
+#  undef g_object_ref
+#endif
 #define g_object_ref                                     rtlookup_g_object_ref
 #define g_object_unref                                   rtlookup_g_object_unref
 #define g_value_init                                     rtlookup_g_value_init
 #define g_value_unset                                    rtlookup_g_value_unset
 #define g_value_get_string                               rtlookup_g_value_get_string
 #define g_value_get_boolean                              rtlookup_g_value_get_boolean
+#define g_type_name                                      rtlookup_g_type_name
 #define orig_g_type_register_static_simple               rtlookup_g_type_register_static_simple
 #define orig_g_type_add_interface_static                 rtlookup_g_type_add_interface_static
 #define orig_g_type_add_instance_private                 rtlookup_g_type_add_instance_private
@@ -374,7 +408,43 @@ static void static_g_log(const gchar *lo
     va_end (args);
 }
 
-static gboolean is_gtk_version_larger_or_equal(guint major, guint minor, guint micro) {
+int check_gtk2_callback(struct dl_phdr_info *info, size_t size, void *pointer)
+{
+    ElfW(Half) n;
+
+    if (G_UNLIKELY(strstr(info->dlpi_name, GDK_LIBRARY_SONAME_V2))) {
+        for (n = 0; n < info->dlpi_phnum; n++) {
+            uintptr_t start = (uintptr_t) (info->dlpi_addr + info->dlpi_phdr[n].p_vaddr);
+            uintptr_t end   = start + (uintptr_t) info->dlpi_phdr[n].p_memsz;
+            if ((uintptr_t) pointer >= start && (uintptr_t) pointer < end) {
+                gtk2_active = 1;
+                /* The gtk version check could have already been cached
+                 * before we were able to determine that gtk2 is in
+                 * use, so force this to FALSE. (Regardless of  the
+                 * _checked value.) */
+                is_compatible_gtk_version_cached = FALSE;
+                return 0;
+            }
+        }
+    }
+    return 0;
+}
+
+static void detect_gtk2(void *pointer)
+{
+    if (gtk2_active)
+        return;
+    /* There is a corner case where a program with plugins loads
+     * multiple plugins, some of which are linked against gtk2, while
+     * others are linked against gtk3. If the gtk2 plugins are used,
+     * this causes problems if we detect gtk3 just on the fact of
+     * whether gtk3 is loaded. Hence we iterate over all loaded
+     * libraries and if the pointer passed to us is within the memory
+     * region of gtk2, we set a global flag. */
+    dl_iterate_phdr(check_gtk2_callback, pointer);
+}
+
+static gboolean is_gtk_version_larger_or_equal2(guint major, guint minor, guint micro, int* gtk_loaded) {
     static gtk_check_version_t orig_func = NULL;
     if(!orig_func)
         orig_func = (gtk_check_version_t)find_orig_function(0, GTK_LIBRARY, "gtk_check_version");
@@ -388,9 +458,19 @@ static gboolean is_gtk_version_larger_or
      * will give us a reference to gtk_check_version. But since
      * that symbol is compatible with gtk3, this doesn't hurt.
      */
-     if (orig_func)
+     if (orig_func) {
+         if (gtk_loaded)
+             *gtk_loaded = TRUE;
         return (orig_func(major, minor, micro) == NULL);
-    return FALSE;
+     } else {
+         if (gtk_loaded)
+             *gtk_loaded = FALSE;
+        return FALSE;
+     }
+}
+
+static gboolean is_gtk_version_larger_or_equal(guint major, guint minor, guint micro) {
+    return is_gtk_version_larger_or_equal2(major, minor, micro, NULL);
 }
 
 static gboolean are_csd_disabled() {
@@ -404,22 +484,27 @@ static gboolean are_csd_disabled() {
 }
 
 static gboolean is_compatible_gtk_version() {
-    /* Marking both as volatile here saves the trouble of caring about
-     * memory barriers. */
-    static volatile gboolean checked = FALSE;
-    static volatile gboolean compatible = FALSE;
+    int gtk_loaded = FALSE;
 
-    if(G_UNLIKELY(!checked)) {
-        if (!is_gtk_version_larger_or_equal(3, 10, 0)) {
+    if(G_UNLIKELY(!is_compatible_gtk_version_checked)) {
+        if (gtk2_active) {
+            is_compatible_gtk_version_cached = FALSE;
+	} else if (!is_gtk_version_larger_or_equal2(3, 10, 0, &gtk_loaded)) {
             /* CSD was introduced there */
-            compatible = FALSE;
+            is_compatible_gtk_version_cached = FALSE;
         } else {
-            compatible = TRUE;
+            is_compatible_gtk_version_cached = TRUE;
         }
-        checked = TRUE;
+        /* If in a dynamical program (e.g. using python-gi) Glib is loaded before
+         * Gtk, then the Gtk version check is executed before Gtk is even loaded,
+         * returning FALSE and caching it. This will not disable CSD if Gtk is
+         * loaded later. To circumvent this, cache the value only if we know that
+         * Gtk is loaded. */
+        if (gtk_loaded)
+            is_compatible_gtk_version_checked = TRUE;
     }
 
-    return compatible;
+    return is_compatible_gtk_version_cached;
 }
 
 static void set_has_custom_title(GtkWindow* window, gboolean set) {
@@ -479,11 +564,18 @@ static GtkStyleProvider *get_custom_css_
       "  border-color: transparent;\n"
       "}\n"
       ".background:not(.tiled):not(.maximized) .titlebar:backdrop,\n"
-      ".background:not(.tiled):not(.maximized) .titlebar {\n"
+      ".background:not(.tiled):not(.maximized) .titlebar,"
+      ".background:not(.tiled):not(.maximized) .titlebar headerbar {\n"
       "  border-top-left-radius: 0;\n"
       "  border-top-right-radius: 0;\n"
-      "}\n"
-      "";
+      "}\n";
+    static int title_skipped = 0;
+
+    const char* env_show_header = getenv("GTK3NOCSD_SHOW_HEADER");
+    if (env_show_header && !strncmp(env_show_header, "1", 2) && !title_skipped) {
+        custom_css += 39; // skip CSS rule that hides title
+        title_skipped = 1;
+    }
 
     if (G_UNLIKELY (provider == NULL)) {
         GtkCssProvider *new_provider;
@@ -507,16 +599,15 @@ static GtkStyleProvider *get_custom_css_
 
 static void add_custom_css (GtkWidget *widget)
 {
-    GtkStyleContext *context = gtk_widget_get_style_context (widget);
     GtkStyleProvider *my_provider = get_custom_css_provider ();
-
-    if (!context || !my_provider)
+    if (!my_provider)
         return;
 
     /* Use a higher priority than SETTINGS, but lower than APPLICATION.
      * add_provider will make sure a given provider is not added twice.
      */
-    gtk_style_context_add_provider (context, my_provider, GTK_STYLE_PROVIDER_PRIORITY_SETTINGS + 50);
+    GdkScreen *screen = gdk_screen_get_default ();
+    gtk_style_context_add_provider_for_screen (screen, my_provider, GTK_STYLE_PROVIDER_PRIORITY_SETTINGS + 50);
 }
 
 // This API exists since gtk+ 3.10
@@ -554,12 +645,6 @@ extern void gtk_window_set_titlebar (Gtk
             }
         }
 
-        /* Remove any potential old title bar. We can't call
-         * the static unset_titlebar() directly (not available),
-         * so we call the full function; that shouldn't have
-         * any side effects. */
-        orig_gtk_window_set_titlebar (window, NULL);
-
         /* The solid-csd class is not removed when the titlebar
          * is unset in Gtk (it's probably a bug), so unset it
          * here explicitly, in case it's set. */
@@ -577,6 +662,13 @@ extern void gtk_window_set_titlebar (Gtk
             g_signal_connect (titlebar, "notify::title",
                         G_CALLBACK (private_info.on_titlebar_title_notify), window);
             private_info.on_titlebar_title_notify (GTK_HEADER_BAR (titlebar), NULL, window);
+
+            /* Hiding GtkHeaderBar when custom title wasn't set (only for GtkDialog windows) */
+            const GtkWidget* custom = gtk_header_bar_get_custom_title(GTK_HEADER_BAR (titlebar));
+            const gchar* window_type = G_OBJECT_TYPE_NAME(window);
+            if (custom == NULL && strcmp(window_type, "GtkDialog")) {
+                gtk_widget_hide(GTK_WIDGET (titlebar));
+            }
         }
 
         gtk_style_context_add_class (gtk_widget_get_style_context (titlebar),
@@ -665,14 +757,10 @@ static void _gtk_header_bar_update_windo
         r = _remove_buttons_from_layout (new_layout, *decoration_layout_ptr);
         if (r == 0)
             *decoration_layout_ptr = new_layout;
-    } else {
-        TLSD->fake_global_decoration_layout = 1;
     }
     info.update_window_buttons (bar);
     if (*decoration_layout_ptr) {
         *decoration_layout_ptr = orig_layout;
-    } else {
-        TLSD->fake_global_decoration_layout = 0;
     }
 }
 
@@ -725,7 +813,7 @@ extern void g_object_get (gpointer _obje
      * g_object_get(). */
 
     va_start (var_args, first_property_name);
-    if (G_UNLIKELY (TLSD->fake_global_decoration_layout)) {
+    if (are_csd_disabled()) {
         name = first_property_name;
         while (name) {
             GValue value = G_VALUE_INIT;
@@ -746,6 +834,10 @@ extern void g_object_get (gpointer _obje
                 if (r == 0)
                     s = new_layout;
                 *v = g_strdup (s);
+            } else if (G_UNLIKELY (strcmp (name, "gtk-dialogs-use-header") == 0)) {
+                gboolean *v = va_arg (var_args, gboolean *);
+                // Save dialog will break if this prop has been set to TRUE (see #13)
+                *v = FALSE;
             } else {
                 G_VALUE_LCOPY (&value, var_args, 0, &error);
                 if (error) {
@@ -789,6 +881,11 @@ extern void gtk_header_bar_set_decoratio
     }
 }
 
+extern gboolean gtk_window_get_decorated (GtkWindow *window)
+{
+    return FALSE;
+}
+
 extern gboolean gdk_screen_is_composited (GdkScreen *screen) {
     /* With Gtk+3 3.16.1+ we reimplement gtk_window_set_titlebar ourselves, hence
      * we don't want to re-use the compositing hack, especially since it causes
@@ -1006,6 +1103,7 @@ GType g_type_register_static_simple (GTy
         if(type_name && G_UNLIKELY(strcmp(type_name, "GtkWindow") == 0)) {
             // override GtkWindowClass
             orig_gtk_window_class_init = class_init;
+            detect_gtk2((void *) class_init);
             if(is_compatible_gtk_version() && are_csd_disabled()) {
                 class_init = (GClassInitFunc)fake_gtk_window_class_init;
                 save_type = &gtk_window_type;
@@ -1018,6 +1116,7 @@ GType g_type_register_static_simple (GTy
         if(type_name && G_UNLIKELY(strcmp(type_name, "GtkDialog") == 0)) {
             // override GtkDialogClass
             orig_gtk_dialog_class_init = class_init;
+            detect_gtk2((void *) class_init);
             if(is_compatible_gtk_version() && are_csd_disabled()) {
                 class_init = (GClassInitFunc)fake_gtk_dialog_class_init;
                 save_type = &gtk_dialog_type;
@@ -1030,6 +1129,7 @@ GType g_type_register_static_simple (GTy
         if(type_name && G_UNLIKELY(strcmp(type_name, "GtkHeaderBar") == 0)) {
             // override GtkHeaderBarClass
             orig_gtk_header_bar_class_init = class_init;
+            detect_gtk2((void *) class_init);
             if(is_compatible_gtk_version() && are_csd_disabled()) {
                 class_init = (GClassInitFunc)fake_gtk_header_bar_class_init;
                 save_type = &gtk_header_bar_type;
@@ -1042,6 +1142,7 @@ GType g_type_register_static_simple (GTy
         if(type_name && G_UNLIKELY(strcmp(type_name, "GtkShortcutsWindow") == 0)) {
             // override GtkShortcutsWindowClass
             orig_gtk_shortcuts_window_init = instance_init;
+            detect_gtk2((void *) instance_init);
             if(is_compatible_gtk_version() && are_csd_disabled()) {
                 instance_init = (GInstanceInitFunc) fake_gtk_shortcuts_window_init;
                 goto out;
@@ -1095,6 +1196,9 @@ static void fake_gtk_dialog_buildable_in
 }
 
 void g_type_add_interface_static (GType instance_type, GType interface_type, const GInterfaceInfo *info) {
+    if (info && info->interface_init)
+        detect_gtk2((void *) info->interface_init);
+
     if(is_compatible_gtk_version() && are_csd_disabled() && (instance_type == gtk_window_type || instance_type == gtk_dialog_type)) {
         if(interface_type == GTK_TYPE_BUILDABLE) {
             // register GtkBuildable interface for GtkWindow/GtkDialog class
@@ -1248,7 +1352,7 @@ out:
 
 static gtk_header_bar_private_info_t gtk_header_bar_private_info ()
 {
-    static volatile gtk_header_bar_private_info_t info = { (gsize) -1, NULL };
+    static volatile gtk_header_bar_private_info_t info = { (gsize) -1, NULL, NULL };
     if (G_UNLIKELY (info.decoration_layout_offset == (gsize) -1)) {
         /* Was only introduced in Gtk+3 >= 3.12. Unlikely that someone is
          * still using such an old version, but be safe nevertheless. */

➤ apt info packaging-dev
Package: packaging-dev
...
Depends: build-essential, debhelper, devscripts, dput-ng | dput | dupload, lintian, sbuild | cowbuilder | pbuilder, quilt
Recommends: apt-file, autoconf, automake, autopkgtest, autotools-dev, bzr-debian, cdbs, cmake, debian-policy, developers-reference | developers-reference-de | developers-reference-fr | developers-reference-ja, dh-autoreconf, dh-make, git-buildpackage, gnome-pkg-tools, gnupg, libtool, piuparts, pkg-kde-tools, svn-buildpackage
Suggests: mercurial-buildpackage

sudo apt install quilt

➤ dpkg -l | grep dput
ii  dput             1.1.3           all          Debian package upload tool

➤ dpkg -l | grep sbuild
ii  libsbuild-perl         0.85.0            all          Library for building Debian binary packages from Debian sources
ii  sbuild                 0.85.0            all          Tool for building Debian binary packages from Debian sources

apt build-dep gtk3-nocsd --simulate

sudo apt build-dep gtk3-nocsd

$ sudo apt-get purge pulseaudio pulseaudio-utils pavucontrol pulseaudio-module-bluetooth pipewire pipewire-bin pipewire-pulse

$ sudo /etc/init.d/alsa-utils force-reload
Shutting down ALSA...done.
Setting up ALSA...done. 

➤ fuser -av $(find /dev/snd -type c 2>/dev/null)
                     USER        PID ACCESS COMMAND
/dev/snd/controlC0:  igor       2245 F.... mate-settings-d
                     igor       2344 F.... mate-volume-con
/dev/snd/pcmC0D0c:
/dev/snd/pcmC0D0p:   igor       3166 F...m firefox-esr
/dev/snd/seq:
/dev/snd/timer:      igor       3166 f.... firefox-esr

➤ ps -A u | grep mate-volume-con
igor      2344  0.0  0.7 483040 59088 ?        Sl   16:27   0:10 mate-volume-control-status-icon

➤ ps -A u | grep mate-settings-d
igor      2245  0.1  0.6 968348 53544 ?        Sl   16:27   0:28 /usr/bin/mate-settings-daemon

➤ apt-file find /usr/bin/mate-volume-control-status-icon 
mate-media: /usr/bin/mate-volume-control-status-icon

➤ apt info mate-media
Package: mate-media
...
Description: MATE media utilities
 MATE media utilities are the audio mixer and the volume
 control applet.

fuser -av $(find /dev/snd -type c 2>/dev/null)

inxi -A

sudo apt install inxi

➤ apt-file find /etc/alsa/conf.d
...
libasound2-plugins: /etc/alsa/conf.d/10-rate-lav.conf
libasound2-plugins: /etc/alsa/conf.d/10-samplerate.conf
libasound2-plugins: /etc/alsa/conf.d/10-speexrate.conf
libasound2-plugins: /etc/alsa/conf.d/50-arcam-av-ctl.conf
libasound2-plugins: /etc/alsa/conf.d/50-jack.conf
libasound2-plugins: /etc/alsa/conf.d/50-oss.conf
libasound2-plugins: /etc/alsa/conf.d/50-pulseaudio.conf
libasound2-plugins: /etc/alsa/conf.d/60-a52-encoder.conf
libasound2-plugins: /etc/alsa/conf.d/60-speex.conf
libasound2-plugins: /etc/alsa/conf.d/60-upmix.conf
libasound2-plugins: /etc/alsa/conf.d/60-vdownmix.conf
libasound2-plugins: /etc/alsa/conf.d/98-usb-stream.conf
libasound2-plugins: /etc/alsa/conf.d/99-pulseaudio-default.conf.example
...

SoundDriver = ALSA