[wxMac 2.8.x] Bug in wxWindowBase::DoGetBestSize() - Help needed

[H]

I already posted this a while ago but did not get an answer. Therefore, 
my next try.
This is the statement causing problems:

    else if ( !GetChildren().empty()
#ifdef __WXMAC__
              && wxHasRealChildren(this)
#endif
              )

There is also a remark related to "wxHasRealChildren" that "scrollbars 
are explicitely children" on the Mac (whatever it means).

Why is wxWindowBase::DoGetBestSize() returning wxSize(0, 0) if the 
window only has scrollbars? I thought it would at least return the size 
needed for the scrollbars (see also my topic related to wxTreeBook).
The real problem is that some modules assume that a window's client size 
is zero or larger. But with this implementation of DoGetBestSize() this 
is not the case anymore, it becomes negative!

Hartwig