Implementing on an inherited type

[ljlevend]

Is there any way to implement on a property or function who's return type is
an inheritor of the corresponding property or function in the interface? For
example, I would like to be able to do the following:

Public Interface ITest
ReadOnly Property TestProperty() As BaseClass
End Interface

Public Class BaseClass
End Class
Public Class InheritedClass
Inherits BaseClass
End Class

Public Class Class1
Implements ITest

Public ReadOnly Property TestProperty() As InheritedClass Implements
ITest.TestProperty
Get
...
End Get
End Property
End Class

Of course the implementation is invalid because TestProperty in Class1 does
not have the required signature (even though it would seem to me that the
above should be valid). I realize that a workaround would be to do the
following:

Private ReadOnly Property TestProperty1() As InheritedClass Implements
ITest.TestProperty
Get
Return Me.TestProperty
End Get
End Property

But, this doesn't seem as efficient as what I'm trying to do.

Thanks,
Lance