I would like Nautilus to tell the window manager what it's size should be.
 A lot of window managers don't have the ability to determine what the size
of the window manager is.  

If we were to use metacity it currently doesn't have the ability to enforce
a size on the application.  I think it should be up to the app to do this.
 I don't know if there is a good ui way to do this.  I refer you to bug
#81802 on Havoc's thought on this feature for Metacity.

I think the simplest thing to do is to make Nautilus report it's size to
the window manager.  This can probably be a post 2.0 feature request.

sri