anchor.diff:  
            // now process all active edges in XOR fashion
            If Assigned(active) Then
  -            stbtt__fill_active_edges(scanline, resultBitmap.Width, active, max_weight);
  +            stbtt__fill_active_edges(@scanline[0], resultBitmap.Width, active, max_weight);
   
            Inc(y);
         end;
  
positive.code:          while step^<>nil do
           begin
              z := step^;
              if (z^.ey <= scan_y) then
              begin
                 step^ := z^.next; // delete from list
                 z^.valid := 0;
                 Dispose(z);
              end else begin
                 Inc(z^.x, z^.dx); // advance to position for current scanline
                 step := @(PStBttActiveEdge((step^)^.next)); // advance through list
              end;
           end;
  
  
negative.code: {$RANGECHECKS OFF}
  
  Type
    TStBttVertex = record
       x,y,cx,cy: Smallint;
       vertexType,padding: Byte;
  