Scrollbar BUG: Scrollbar doesn't work in the after expand the subGrid

I'm using UI-Grid to create subGrid and I need to retrieve data after expand. However, the scrollbar never work correctly after expand the row!

To reproduce this bug, go to this page: http://ui-grid.info/docs/#/tutorial/216_expandable_grid

You can reproduced this issue with any subgrid demo Use the "Retrieve data for subGrid when expanding" demo is easier to see it

Reproduce steps:

1. Expand any row
2. Then scroll to the very bottom.
3. Scroll up and down a bit
4. The grid become completely useless now

Here is how it looks like

For my own case, it works even worse!