[libdazzle] multi-paned: unregister child window before destroying it

[Christian Hergert <chergert src gnome org>]

commit 71095392c002aca6fd1e7350989795da6cb7ba29
Author: Christian Hergert <chergert redhat com>
Date:   Sat Jul 28 01:05:28 2018 -0700

    multi-paned: unregister child window before destroying it

 src/widgets/dzl-multi-paned.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/widgets/dzl-multi-paned.c b/src/widgets/dzl-multi-paned.c
index 1e60330..a08f694 100644
--- a/src/widgets/dzl-multi-paned.c
+++ b/src/widgets/dzl-multi-paned.c
@@ -383,6 +383,7 @@ dzl_multi_paned_destroy_child_handle (DzlMultiPaned      *self,
 
   if (child->handle != NULL)
     {
+      gtk_widget_unregister_window (GTK_WIDGET (self), child->handle);
       gdk_window_destroy (child->handle);
       child->handle = NULL;
     }