The case for RuntimeWarning: the object isn't necessarily *broken* as such (most things will still work), but pickling and some introspection features may not work properly.

The case for DeprecationWarning: breaking picking and introspection is bad when the fix (setting __module__) is straightforward, so this should eventually become an AttributeError:

    AttributeError: __module__ not set on builtin type tkapp

My own preference is for the latter - eventually making it a hard requirement to specify the module name properly. Even true builtins officially live in the builtins module:

    >>> str.__module__
    'builtins'