diff --color -U 5 -r -Z -B ./org/gtk/gtkheaderbar.c ./mod/gtk/gtkheaderbar.c
--- ./org/gtk/gtkheaderbar.c	2018-01-15 14:21:38.000000000 +0100
+++ ./mod/gtk/gtkheaderbar.c	2018-05-30 02:00:19.887457964 +0200
@@ -298,10 +298,31 @@
       priv->titlebar_end_separator = NULL;
     }

   priv->titlebar_icon = NULL;

+  gboolean csd_cleaned_headerbar = (!gtk_style_context_has_class (gtk_widget_get_style_context (toplevel), "csd") &&
+                                    !gtk_style_context_has_class (gtk_widget_get_style_context (toplevel), "solid-csd"));
+  if (csd_cleaned_headerbar)
+    {
+      if (priv->label_box != NULL)
+        {
+          priv->label_box = NULL;
+          priv->title_label = NULL;
+          priv->subtitle_label = NULL;
+        }
+      static gboolean style_added = FALSE;
+      if (!style_added)
+        {
+          style_added = TRUE;
+          GtkCssProvider *provider = gtk_css_provider_new ();
+          gtk_css_provider_load_from_data (provider,
+            "headerbar, .titlebar { border-radius: 0; border-top: 0; box-shadow: none; }", -1, NULL);
+          gtk_style_context_add_provider_for_screen (gtk_widget_get_screen (widget),
+            GTK_STYLE_PROVIDER (provider), GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+        }
+    }
   if (!priv->shows_wm_decorations)
     return;

   direction = gtk_widget_get_direction (widget);

@@ -325,10 +346,12 @@

   is_sovereign_window = (!gtk_window_get_modal (window) &&
                           gtk_window_get_transient_for (window) == NULL &&
                           gtk_window_get_type_hint (window) == GDK_WINDOW_TYPE_HINT_NORMAL);

+  if (csd_cleaned_headerbar)
+      layout_desc = strstr (layout_desc, "menu") ? g_strdup ("menu") : g_strdup ("");
   tokens = g_strsplit (layout_desc, ":", 2);
   if (tokens)
     {
       for (i = 0; i < 2; i++)
         {
@@ -389,13 +412,13 @@
                   accessible = gtk_widget_get_accessible (button);
                   if (GTK_IS_ACCESSIBLE (accessible))
                     atk_object_set_name (accessible, _("Application menu"));

                   priv->titlebar_icon = image;
-                  if (!_gtk_header_bar_update_window_icon (bar, window))
+                  if (csd_cleaned_headerbar || !_gtk_header_bar_update_window_icon (bar, window))
                     gtk_image_set_from_icon_name (GTK_IMAGE (priv->titlebar_icon),
-                                                  "application-x-executable-symbolic", GTK_ICON_SIZE_MENU);
+                                                  "pan-down-symbolic", GTK_ICON_SIZE_MENU);
                 }
               else if (strcmp (t[j], "minimize") == 0 &&
                        is_sovereign_window)
                 {
                   button = gtk_button_new ();
@@ -1359,10 +1382,11 @@
     }

   gtk_widget_set_visible (priv->subtitle_sizing_label, priv->has_subtitle || (priv->subtitle && priv->subtitle[0]));

   g_object_notify_by_pspec (G_OBJECT (bar), header_bar_props[PROP_SUBTITLE]);
+  g_object_notify_by_pspec (G_OBJECT (bar), header_bar_props[PROP_TITLE]);
 }

 /**
  * gtk_header_bar_get_subtitle:
  * @bar: a #GtkHeaderBar
diff --color -U 5 -r -Z -B ./org/gtk/gtkwindow.c ./mod/gtk/gtkwindow.c
--- ./org/gtk/gtkwindow.c	2018-01-15 14:21:38.000000000 +0100
+++ ./mod/gtk/gtkwindow.c	2018-05-30 02:00:46.846359548 +0200
@@ -4161,10 +4161,12 @@
                           GtkWindow    *self)
 {
   const gchar *title;

   title = gtk_header_bar_get_title (titlebar);
+  if (gtk_header_bar_get_subtitle (titlebar))
+    title = g_strconcat (title, " — ", gtk_header_bar_get_subtitle (titlebar), NULL);
   gtk_window_set_title_internal (self, title, FALSE);
 }

 /**
  * gtk_window_set_titlebar:
@@ -9274,10 +9276,11 @@

 static void
 gtk_window_do_popup (GtkWindow      *window,
                      GdkEventButton *event)
 {
+  if (!window->priv->client_decorated) return;
   if (!gdk_window_show_window_menu (_gtk_widget_get_window (GTK_WIDGET (window)),
                                     (GdkEvent *) event))
     gtk_window_do_popup_fallback (window, event);
 }