Hello,

there are numerous problems with navigating / scrolling on the DataGrid using keyboard keys.

Here is the test page:

https://stackblitz.com/edit/react-brdhufzd

1. Grid with navigatable=true:

- arrow keys - when you select a cell to be able to navigate and then  keep pressing down and then up, it's not posible to come back to the first record. You need to use the mouse.

- Page up/down keys work the other way round, also sometimes is not possible to come back to the first record, the scrollbar does not show the current position.

- It starts to work correctly after using the arrow keys and page up/down keys alternatively couple of times

2. Grid with navigatable=false:
- arrow,Page up/down keys and scrollbar work correctly

3. Grid with navigatable=true and nested inside Window:
- works the same way as not nested - the same problems occur

4. Grid with navigatable=false and nested inside Window:
- arrow keys move the window instead of navigating the grid
- Page up/down don't work at all