pImpl in D

[Satoshi via Digitalmars-d]

Hi,
do someone have any experience with pImpl and inheritance in D?
I tried something like:

// FooPrivate.d
class FooPrivate {
    int a;
}


// BarPrivate.d
import FooPivate;

class BarPrivate : FooPrivate {
    string b;
}


// Foo.d
import FooPrivate;

class Foo {
    protected FooPrivate m_private;

    this() { m_private = new FooPrivate; }
}


// Bar.d
import Foo;
import FooPrivate;
import BarPrivate;

class Bar : Foo {
    this() { m_private = new BarPrivate; }
}


And public interface
// Foo.di
class FooPrivate;
class Foo {
    private FooPrivate m_private;
}


Bar.d looks like it imported Foo with forward referenced 
FooPrivate and is unable to resolve it by importing FooPrivate.

Is this bug?
Do you know about any *less verbose* design pattern how I can 
hide implementaion details from .di files?

Thanks!