I have a grid with virtualization on and with multi-line data in some rows, meaning the row height's are not the same throughout the grid. When more data is added, the grid will scroll automatically for no reason. For example, the grid is scrolled so that the 10 row is the topmost. Added more data to the bottom of the grid and the topmost row is not longer the 10th, although the existing data in the grid did not change.
There is no TopMostRow property and the scrollbar offsets do not change although the view-port offset definitely did change.
A well behaved grid would only modify the scroll bar itself to indicate more data in the grid.