Here are a couple of issues I've come across in 120b (they were in 120a as well, at least the first one was):

1. Any new Document Pane has a blank line at the top.

2. If you have the focus on the Document Pane, and you alt-tab away, then back, the focus has switched to the Grid. Making it even more confusing, this happens only every second time you alt-tab. I was taking notes on something, alt-tabbing back and forth, and it took me a while to work out why my notes kept ending up in the Grid rather than the Doc Pane.

- David F.