widgets such as `Records` and `Facet` that display some part
of a search result.
-* `VOID hideWhenNarrow()` --
- Registers that this widget should hide itself when the page
- becomes "narrow" -- that is, fewer pixels in width that the
- threshhold value specified by the top-level configuration item
- `responsive_design_width`. Should be used for "unimportant"
- widgets that can be omitted from the mobile version of a site.
-
-* `expandValue()` --
- FIXME: either document this or remove it from the API.
-
* `subwidget(type, overrides, defaults)` --
Returns the HTML of a subwidget of the specified type, which
can then be inserted into the widget using the