[wxMac] please retest scrolling codes

[Stefan Csomor]

Hi

in the everlasting quest for getting correct behavior and optimal
performance, I've changed the scrolling code in wxScrolledWindow and
wxWindowMac again. I did a regression test on the problematic cases
known to me (wheel scrolling in richtextctrl and scrolling in wxgrid),
but I'd really like to invite everybody to test their code either
against CVS HEAD, CVS WX_2_8_BRANCH or the upcoming 2.8.4 RC 2

Thanks,

Stefan