Two types need to know about each other

@Czar Flavius : What you're doing sounds perfectly fine.
It's perfectly ok to have a parent reference. It's usefull for all sorts of stuff.
I'd usually put the list in the parent type like this:

type Tgame
   field shapes_inplay:tlist = New tlist 
end type

I don't get tonyg's "' pointing to tshape.list" comment.

The usefull thing is that each Tgame type can have its own list of shapes.
As far as I can tell tonyg ends up with only one list for the tshape type.