[D4] Bug when dragging variable byte classes in CHB

I've described this before in my post of 2000/8/16 on the old newsgroup.
The problem seems still to exist in D4.

To reproduce:

    Create a subclass of Dictionary -- say Eg1.
    Create a subclass of Eg1 -- say Eg2.
    Drag Eg2 to be a direct subclass of Dictionary.

I get an error popup:

    Subclass of an indexed class must also be indexed.

(My original post described what I thought was going wrong, and how to fix
it, but I haven't checked that the same analysis applies to D4)

    -- chris