[gnome-klotski/ricotz/vala] Reference of [GtkChild] fields is handled by GtkBuilder, type must be unowned

[Rico Tzschichholz <ricotz src gnome org>]

commit eee3df025ee4031456463faa8bd9a1db007ba73b
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Wed Mar 17 11:20:26 2021 +0100

    Reference of [GtkChild] fields is handled by GtkBuilder, type must be unowned

 src/klotski-window.vala | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)
---
diff --git a/src/klotski-window.vala b/src/klotski-window.vala
index f6f2836..a3f1e6a 100644
--- a/src/klotski-window.vala
+++ b/src/klotski-window.vala
@@ -44,20 +44,20 @@ private class KlotskiWindow : ApplicationWindow
     private const string KEY_LEVEL = "level";
 
     /* Widgets */
-    [GtkChild] private HeaderBar headerbar;
-    [GtkChild] private Stack stack_packs;
-    [GtkChild] private Stack stack_puzzles;
-    [GtkChild] private Popover puzzles_popover;
-    [GtkChild] private MenuButton game_menubutton;
-    [GtkChild] private MenuButton main_menubutton;
+    [GtkChild] private unowned HeaderBar headerbar;
+    [GtkChild] private unowned Stack stack_packs;
+    [GtkChild] private unowned Stack stack_puzzles;
+    [GtkChild] private unowned Popover puzzles_popover;
+    [GtkChild] private unowned MenuButton game_menubutton;
+    [GtkChild] private unowned MenuButton main_menubutton;
     private PuzzleView view;
 
-    [GtkChild] private TreeView treeview_huarong;
-    [GtkChild] private TreeView treeview_challenge;
-    [GtkChild] private TreeView treeview_skill;
+    [GtkChild] private unowned TreeView treeview_huarong;
+    [GtkChild] private unowned TreeView treeview_challenge;
+    [GtkChild] private unowned TreeView treeview_skill;
 
-    [GtkChild] private Grid main_grid;
-    [GtkChild] private Button unfullscreen_button;
+    [GtkChild] private unowned Grid main_grid;
+    [GtkChild] private unowned Button unfullscreen_button;
 
     /* Actions, to disable or enable */
     private SimpleAction prev_pack;