[gnome-chess] Preferences dialog should be transient for the main window

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 138c3298a5ba83780acbfaba293b35f7ba8b20ea
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sat Mar 11 11:42:24 2017 -0600

    Preferences dialog should be transient for the main window
    
    It doesn't work if using the GtkWindow API, only if using the GtkDialog
    API.

 src/gnome-chess.vala |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/gnome-chess.vala b/src/gnome-chess.vala
index a68861d..35d0c3f 100644
--- a/src/gnome-chess.vala
+++ b/src/gnome-chess.vala
@@ -1702,7 +1702,7 @@ Copyright © 2015–2016 Sahil Sareen""";
     {
         if (preferences_dialog != null)
         {
-            preferences_dialog.present ();
+            preferences_dialog.run ();
             return;
         }
 
@@ -1780,7 +1780,7 @@ Copyright © 2015–2016 Sahil Sareen""";
             difficulty_combo.sensitive = false;
         }
 
-        preferences_dialog.present ();
+        preferences_dialog.run ();
     }
 
     private void set_combo (Gtk.ComboBox combo, int value_index, string value)