MSBlitCut On/Off ; 0=Paste stencil/cookie, <>0=Cut using stencil/cookie

Selects wether to perform a stencil-cut or a normal stencil-blit when performing
MSblit and MSBlock. If SBlitCut is Off, a Shape's graphic is blitted to the
Bitmap's graphic and the Shape's cookie is blitted to the Bitmap's stencil. If
SBlitCut is On, the destination Bitmap's stencil will be used to protect areas of
the Bitmap's graphic rather than copying the cookie to the stencil, which has the
effect of looking as thought the operation is performed `behind' the protected
areas.