Create Grid with many rows - focus is jumping

[swacsa]

If I try to create a grid with more than 10 rows the focus is moving up and down:

1. I go up to press the Add button 3 times, and scroll down to write the field names
2. When I click in a new Untitled row field the focus jumping up.
3. When I start to write something to the field the focus is jumping back.
   https://www.screencast.com/t/rtckvvt9r