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 02:35:02.521000924 +0200
@@ -7953,11 +7953,11 @@
                         GdkEventWindowState *event)
 {
   GtkWindow *window = GTK_WINDOW (widget);
   GtkWindowPrivate *priv = window->priv;
 
-  if (event->changed_mask & GDK_WINDOW_STATE_FOCUSED)
+  if ((event->changed_mask & GDK_WINDOW_STATE_FOCUSED) && priv->client_decorated)
     ensure_state_flag_backdrop (widget);
 
   if (event->changed_mask & GDK_WINDOW_STATE_FULLSCREEN)
     {
       priv->fullscreen =