[gtk] entry completion: Avoid critical warnings

[Matthias Clasen <matthiasc src gnome org>]

commit 9e0f43e8cba45015487c692058c002f56087b9b8
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Aug 20 19:15:27 2018 +0000

    entry completion: Avoid critical warnings
    
    We must not call move-to-rect unless we have
    a transient parent.

 gtk/gtkentrycompletion.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)
---
diff --git a/gtk/gtkentrycompletion.c b/gtk/gtkentrycompletion.c
index bf1a7a425c..acb7f04425 100644
--- a/gtk/gtkentrycompletion.c
+++ b/gtk/gtkentrycompletion.c
@@ -1461,14 +1461,16 @@ _gtk_entry_completion_resize_popup (GtkEntryCompletion *completion)
       gtk_tree_path_free (path);
     }
 
-  gdk_surface_move_to_rect (_gtk_widget_get_surface (completion->priv->popup_window),
-                            &allocation,
-                            GDK_GRAVITY_SOUTH,
-                            GDK_GRAVITY_NORTH,
-                            GDK_ANCHOR_FLIP_Y | GDK_ANCHOR_SLIDE_X,
-                            0, 0);
-
-  gtk_widget_show (completion->priv->popup_window);
+  if (gtk_window_get_transient_for (GTK_WINDOW (completion->priv->popup_window)))
+    {
+      gdk_surface_move_to_rect (_gtk_widget_get_surface (completion->priv->popup_window),
+                                &allocation,
+                                GDK_GRAVITY_SOUTH,
+                                GDK_GRAVITY_NORTH,
+                                GDK_ANCHOR_FLIP_Y | GDK_ANCHOR_SLIDE_X,
+                                0, 0);
+      gtk_widget_show (completion->priv->popup_window);
+   }
 }
 
 static void