This one is all manual. The arrows were manual before and the
header sections are now plain rectangles. Removes one usage
of HIThemeDrawButton and related logic together with a cached
pixmap and its rendering.
Still broken in some places, but not worse than before. In
particular, sunken or selected header sections will not render
the left hand side section separator properly. Look can be
improved in the header label with different shades for the
selected or current rows/columns.
Change-Id: I6b1c1f529909341bbf72e82e5a3fc61905c75fa8
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
c1780b9322