Scroll issue with table rows

I have implemented it for table rows. It is working fine i am getting the old and new index. Problem is when my table rows are more and we have to scroll it to get them in view then when i drag the row it till the viewport ends. It is not scrolling the table list as i touched to the top of the window. I was able to do scroll by scroller on mouse but problem is drag is not accepted on the rows that came on screen after scroll.

Can anyone please help me how to diagnose this issue or any suggestion to resolve this problem.