private void doMousePressed(MouseEvent event) {
            scrollbar.setValueIsAdjusting(true);
            captureCurrentMousePosition(event);

            if (getThumbBounds().contains(iMousePoint)) {
                doMousePressedOnThumb();
            } else if (getSupportsAbsolutePositioning() && SwingUtilities.isMiddleMouseButton(event)) {
                doMiddleMouseButtonPressedOnTrack(event);
            } else if (getTrackBounds().contains(iMousePoint)) {
                doMousePressedOnTrack();
            }
        }