vertical alignment of dynamics and `\after`

[Werner LEMBERG]

Please consider this small example.


```
{
  f'1\f\> | f'1\p
}

{
  \after 4 \> f'1\f | f'1\p
}
```

Is there a way to make the second staff behave like the first one,
i.e., to tell LilyPond that `f`, `\>`, and `p'` form a group and
should be placed into the same `DynamicLineSpanner` object?


    Werner