object.d

[Ty Tower]

Thanks Lars
Now Ok " object.di" is an interface file so it loads a lesser part of "object.d". Not all of "object.d"

So I am experimenting with "dwt" which I have in  directory " dwt-linux-tango"  
Trying to compile that I get an error :-
[tytower at linuxbox TangoExamples]$ dmd dwt-linux-tango/layout/GridLayout.d
object.d: module object cannot read file 'object.d'

So this is a tango compatible file why is it looking for "object.d"  ?