MMaskScrollStencilToCookie X1.w,Y1.w,Width.w,Height.w,X2.w,Y2.w[,SourceBitmapNum.w] ;Copy stencil2cookie & cut

Does the same as MMaskScroll except that the source of the operation will be a
chunky Bitmap's stencil which will be mask-blitted to the cookie of a chunky
Shape.