How does one set the default language for a new node to be the same as the ui language?

In fact I'd like to do away with the ANY option altogether which, as far as I can see, can be done by
removing "array('-' => 'Any') , "
from
"$options = array_merge(array('-' => 'Any') , $options);"
in the localizernode.module

It does not in itself do what I want and I cannot figure out how to do the rest.

Any ideas please?