Application: Remove bind/unbind_busy_property().
Application: Remove bind/unbind_busy_property().

Leaving it commented out with a TODO, because I'm not sure if we
want to pass the ObjectBase by RefPtr, or not, or both. Let's leave this
until we have some use for it.

GNOME/glibmm,GNOME/glibmm,GNOME/glibmm,GNOME/glibmm,GNOME/glibmm