treeview unreasonable behaviour

[D M <isaac belial pl eu org>]

        Hello.

        I'm writing a custom tree model. It' contains a huge amount of
data. I noticed a very odd behaviour; when the item is expanded
the treeview asks me to retrieve all it's child entries (even if  
there is no chance they will be displayed at the moment).
Once all data are retrieved it begins to act quite all right,
i.e. it informs me when items goes out of scope, so I can 
release it.
        Is it a bug or there is some rationale behind it?

        Thank you.

-- 
DM