public int getPreferredWidth(Outline outline) {
		int preferredWidth = getPreferredHeaderWidth();
		OutlineModel model = outline.getModel();
		for (Row row : model.getRows()) {
			int width = getRowCell(row).getPreferredWidth(row, this) + model.getIndentWidth(row, this);
			if (width > preferredWidth) {
				preferredWidth = width;
			}
		}
		return preferredWidth;
	}