Using PtOSContainer

Is it possible ( and usefull) to imbricate PtOSContainer?
I’ve tried to do one PtOSContainer containing other PtOSContainer, but it doesn’t seem to work fine.

I have probleme whith PtOSContainer with a lot of element:
My PtOSContainer is containing 500 PtRaw widgets.
If I modify the attribut of some 500 widget and call PtDamageWidget on each
the redraw is fast. ( ~ 10 ms)
If I modify the attribut of a lot of widget and call PtDamageWidget on the PtOSContainer the redraw is fast ( ~100ms).
If I modify the attribut of a lot of widget and call PtDamageWidget on each the redraw is very slow ( ~10 s).

It seems that the redraw when damaging each elements (N)
is in N².

Did some one knows much about this?