examples: Add a GtkStack to the examples
examples: Add a GtkStack to the examples

Clicking on the "clickety" button in the gtk-clutter-test
will toggle, in a GtkStack, between a label, and a clutter-gtk
stage. It doesn't take very long to see the display artifacts after
that.

https://bugzilla.gnome.org/show_bug.cgi?id=695737

GNOME/clutter-gtk,GNOME/clutter-gtk