[gtk/leak-fixes: 2/4] gtk-demo: Fix a memory leak

[Matthias Clasen <matthiasc src gnome org>]

commit e0786a4a00139826c8d0a60de704252fa2bb877c
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Aug 7 15:15:18 2020 -0400

    gtk-demo: Fix a memory leak
    
    The colors demo was leaking a reference to its model.
    This was showing up as crash when you manage to close
    both the demo window and the main window while the
    sorting is ongoing.

 demos/gtk-demo/listview_colors.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/demos/gtk-demo/listview_colors.c b/demos/gtk-demo/listview_colors.c
index b63f2366e0..c8cf07cdba 100644
--- a/demos/gtk-demo/listview_colors.c
+++ b/demos/gtk-demo/listview_colors.c
@@ -1118,6 +1118,8 @@ do_listview_colors (GtkWidget *do_widget)
       gtk_header_bar_pack_end (GTK_HEADER_BAR (header), box);
 
       g_object_bind_property (dropdown, "selected-item", gridview, "factory", G_BINDING_SYNC_CREATE);
+
+      g_object_unref (selection);
     }
 
   if (!gtk_widget_get_visible (window))