--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -6025,9 +6025,6 @@
   GtkWindowPrivate *priv = window->priv;
   const gchar *csd_env;

-  if (priv->csd_requested)
-    return TRUE;
-
   if (!priv->decorated)
     return FALSE;

@@ -6035,28 +6032,6 @@
     return FALSE;

   csd_env = g_getenv ("GTK_CSD");
-
-#ifdef GDK_WINDOWING_BROADWAY
-  if (GDK_IS_BROADWAY_DISPLAY (gtk_widget_get_display (GTK_WIDGET (window))))
-    return TRUE;
-#endif
-
-#ifdef GDK_WINDOWING_WAYLAND
-  if (GDK_IS_WAYLAND_DISPLAY (gtk_widget_get_display (GTK_WIDGET (window))))
-    return TRUE;
-#endif
-
-#ifdef GDK_WINDOWING_MIR
-  if (GDK_IS_MIR_DISPLAY (gtk_widget_get_display (GTK_WIDGET (window))))
-    return TRUE;
-#endif
-
-#ifdef GDK_WINDOWING_WIN32
-  if (g_strcmp0 (csd_env, "0") != 0 &&
-      GDK_IS_WIN32_DISPLAY (gtk_widget_get_display (GTK_WIDGET (window))))
-    return TRUE;
-#endif
-
   return (g_strcmp0 (csd_env, "1") == 0);
 }