behaviour more consistent with other ports. As a side effect
now wxCalendarControl works correctly under wxMotif, too.
Fixed wxWindow::ScrollWindow drawing artifacts when child
controls are involved.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@19835 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775