I'm opposed to this patch. As a design principle, any class should
always call its base class' __init__, unless that is known to be empty.

With this patch, the base __init__ call becomes conditional, which hints
at a design bug of the entire class hierarchy.

I don't quite understand *what* the problem is. If Screen is intended to
be a singleton, then the right fix would be to make Screen a function,
which maintains a singleton reference, and Screen be renamed to _Screen.

The fact that the same design bug already exists in 3.0 doesn't mean it
should be backported to 2.6.