Regression from commit c9175a1b
(SwViewShell::ImplEndAction: avoid direct PaintDesktop(), 2015-07-03),
the problem is that while going via InvalidateWindows() is fine for the
double-buffering case, it has side effects when painting directly, so
revert back to the old code in that case.

Change-Id: Ib1e3b143f5cfe2c6ab8b102a1a2064900282f136
(cherry picked from commit 222f10e7)
Reviewed-on: https://gerrit.libreoffice.org/17835Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>