Shrinking combo boxes in Form

I have a Form. I’m setting a BeanItem on it as its item data source. I commit the form.

The commit operation is wired up to a DAO which produces a new copy of the committed object. I grab that new copy, wrap it up in a new BeanItem, and setItemDataSource on the new bean item.

The custom field factory I’ve installed renders certain properties as combo boxes. On initial form construction, all the combo boxes are of the appropriate length. But when I install the new BeanItem, all the combo boxes shrink down to what looks like possibly a 25 or so character length.

To my eyes, it looks like on the initial form construction, the contents of the combo boxes are available so that Vaadin can (perhaps) use their size in computing the combo boxes’ lengths, but then, for whatever reason, when I call setItemDataSource() again it’s like the contents aren’t being used for such calculations.

What am I doing wrong? Or is this a known bug?