<DataType> void paint() {
    Canvas c = Canvas.get();

    CellStamp<DataType> stamp;
    int y = 0;
    for (int i = 0; i < model.getRowCount(Section.SCROLLABLE); i++) {
      RowAddress address = viewport.createAddress(i, Section.SCROLLABLE);
      @SuppressWarnings("unchecked")
      DataType datum = (DataType) model.get(address);
      stamp = stampFactory.getStamp(address, datum);

      Axis.Span stampSpan = new Axis.Span(Axis.V, y, stamp.getSpan(Axis.V, datum));
      if (viewport
          .getCellPainter()
          .isRowVisible(stampSpan, RowVisibilityType.ACKNOWLEDGE_PARTIAL)) {
        // WIP: BG such as highlight needs to paint outside this inset I just pushed
        c.pushBounds(
            ListModelPainter.CELL_TEXT_INSET, y, viewport.getBounds().width, stampSpan.span);
        stamp.paint(c, address, datum);
        c.popBounds();
      }

      y += stampSpan.span;
    }
  }
 // RevalidateWidthNotification to self
 <DataType> int getContentHeight() {
   int height = viewport.getCellPainter().staticContent.northSpan;
   for (int i = 0; i < model.getRowCount(Section.SCROLLABLE); i++) {
     RowAddress address = viewport.createAddress(i, Section.SCROLLABLE);
     @SuppressWarnings("unchecked")
     DataType datum = (DataType) model.get(address);
     CellStamp<DataType> stamp = stampFactory.getStamp(address, datum);
     height += stamp.getSpan(Axis.V, datum);
   }
   return height;
 }
  @SuppressWarnings("unchecked")
  @Override
  public void compositionCompleted() {
    viewport =
        (CellViewportComposite<ListModelPainter>)
            CompositionRegistry.getComposite(CellViewportComposite.class);
    viewport.getComponent().installHandler(this);

    model = CompositionRegistry.getService(ListDataModel.class);
    stampFactory = CompositionRegistry.getService(CellStamp.Factory.class);
  }
 private <DataType> int calculateRowTop(int row) {
   int position = 0;
   for (int i = 0; i < row; i++) {
     RowAddress address = viewport.createAddress(i, Section.SCROLLABLE);
     @SuppressWarnings("unchecked")
     DataType datum = (DataType) model.get(address);
     CellStamp<DataType> stamp = stampFactory.getStamp(address, datum);
     position += stamp.getSpan(Axis.V, datum);
   }
   return position;
 }
 @Override
 public UserInterfaceActor getActor() {
   return viewport.getComponent().getActor();
 }