public void drawBackground(Graphics2D g2, CategoryPlot plot,
                               Rectangle2D dataArea) {

        float x0 = (float) dataArea.getX();
        float x1 = x0 + (float) Math.abs(this.xOffset);
        float x3 = (float) dataArea.getMaxX();
        float x2 = x3 - (float) Math.abs(this.xOffset);

        float y0 = (float) dataArea.getMaxY();
        float y1 = y0 - (float) Math.abs(this.yOffset);
        float y3 = (float) dataArea.getMinY();
        float y2 = y3 + (float) Math.abs(this.yOffset);

        GeneralPath clip = new GeneralPath();
        clip.moveTo(x0, y0);
        clip.lineTo(x0, y2);
        clip.lineTo(x1, y3);
        clip.lineTo(x3, y3);
        clip.lineTo(x3, y1);
        clip.lineTo(x2, y0);
        clip.closePath();

        Composite originalComposite = g2.getComposite();
        g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,
                plot.getBackgroundAlpha()));

        // fill background...
        Paint backgroundPaint = plot.getBackgroundPaint();
        if (backgroundPaint != null) {
            g2.setPaint(backgroundPaint);
            g2.fill(clip);
        }

        GeneralPath leftWall = new GeneralPath();
        leftWall.moveTo(x0, y0);
        leftWall.lineTo(x0, y2);
        leftWall.lineTo(x1, y3);
        leftWall.lineTo(x1, y1);
        leftWall.closePath();
        g2.setPaint(getWallPaint());
        g2.fill(leftWall);

        GeneralPath bottomWall = new GeneralPath();
        bottomWall.moveTo(x0, y0);
        bottomWall.lineTo(x1, y1);
        bottomWall.lineTo(x3, y1);
        bottomWall.lineTo(x2, y0);
        bottomWall.closePath();
        g2.setPaint(getWallPaint());
        g2.fill(bottomWall);

        // higlight the background corners...
        g2.setPaint(Color.lightGray);
        Line2D corner = new Line2D.Double(x0, y0, x1, y1);
        g2.draw(corner);
        corner.setLine(x1, y1, x1, y3);
        g2.draw(corner);
        corner.setLine(x1, y1, x3, y1);
        g2.draw(corner);

        // draw background image, if there is one...
        Image backgroundImage = plot.getBackgroundImage();
        if (backgroundImage != null) {
            Rectangle2D adjusted = new Rectangle2D.Double(dataArea.getX()
                    + getXOffset(), dataArea.getY(),
                    dataArea.getWidth() - getXOffset(),
                    dataArea.getHeight() - getYOffset());
            plot.drawBackgroundImage(g2, adjusted);
        }

        g2.setComposite(originalComposite);