Change timescroller's position

If timescroller use centre of scroll ber as its position centre, it can't reach top and bottom of table.
![ios simulator screen shot may 22 2013 6 37 02 pm](https://f.cloud.github.com/assets/291175/547459/b2055722-c2c3-11e2-9698-a5cb4eaba8ea.png)

I tried to change Timescroller's position. 
![ios simulator screen shot may 22 2013 6 37 31 pm](https://f.cloud.github.com/assets/291175/547460/b7289bc4-c2c3-11e2-8855-cc2d9c004139.png)