Invalidate less on entering/leaving header/footer

Instead of invalidating the entire window, just invalidate the
parts that need to change.

Invalidate a sequence of Rectangles rather than bundle them
into a vcl::Region. Currently Window::Invalidate(const vcl::Region&...
does a LogicInvalidate(rRegion.GetBoundRect()) so get a mega rectangle
that covers everthing which is the opposite of what I want to get here.
It might be worth using GetRegionRectangles there.

Change-Id: Idc3f5f7d19dd57da725072ec4161d932c0c26902
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/154973
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>

0 files changed, 0 insertions, 0 deletions