Inserting newline sometimes causes strange renders

Thanks for this great library! I came across the behavior below today. It seems as if inserting text renders differently than typing the text from start to finish (or copy-pasting it).

For example, below, the text is
```
insert one newlin
e
```

but looks differently if typed from start-to-fnish or if the newline is inserted.

This seems to happen when inserting a non-newline character would cause wrapping to occur.