MScrollStencil X1.w,Y1.w,Width.w,Height.w,X2.w,Y2.w[,SourceBitmapNum.w] ;

Does the same as MScroll but with regards to the stencil of chunky Bitmap
objects. Source and destination are chunky Bitmap object's stencils. The source
Bitmap's stencil will be copied into the destination Bitmap's stencil.