Don't move the fast scroll thumb with a list on overscroll.

    public void draw(Canvas canvas) {

        super.draw(canvas);

        if (mFastScroller != null) {

            final int scrollY = mScrollY;

            if (scrollY != 0) {

                // Pin the fast scroll thumb to the top/bottom during overscroll.

                int restoreCount = canvas.save();

                canvas.translate(0, (float) scrollY);

                mFastScroller.draw(canvas);

                canvas.restoreToCount(restoreCount);

            } else {

                mFastScroller.draw(canvas);

            }

        }

    }

    @Override

    public boolean onInterceptTouchEvent(MotionEvent ev) {