Some make corrections for HP and related,

  Some make corrections for HP and related,
  Changed refresh order so that window-less widgets
    don't get overdrawn anymore,
  Prevent GTK from filtering our supposedly unneeded
    expose events,
  Block all expose calls if a resize is requested and
    do a full redraw then, thus removing flicker and
    behaving like wxMSW,
  Moved some doubled expose and draw code from GtkPizza
    to the respective callbacks in window.cpp,
  Set idle priority to a higher value (which should
    indicate a lower priority if I interpret glib.h
    correctly) but the desired side-effect didn't
    really show up.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@6533 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775