Why are ImportSelectors not Trees?

Hi all

I've been wondering about this for quite some time: why are ImportSelectors
not subclasses of Tree? Is there a reason for this, or is it just not
necessary (for the compiler)? It would make my life easier if they were trees
as well, so I can treat them uniformly in the refactorings.

Should I take the time to write a patch?

Cheers

Mirko