wined3d_swapchain_present() will invalidate everything except
WINED3D_LOCATION_DRAWABLE, which means a partial blit to the front-buffer
afterwards might need to read the drawable contents back to the texture. For
P8 front-buffers that's problematic, because the original palette indices are
lost. We may want to improve the wined3d side of this to avoid reading back
the drawable, but copying the entire surface in ddraw in this situation seems
like a good idea regardless.
Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>