Now always call both check_widget and make_widget_from_value. This
should make it a lot less confusing when randomly trying to create
a widget as all ways to do it slowly converge toward an unified
one.
ldoc has a magical `@classmod` module type which tries to detect
what is a method and what is a static function. It fails about as
often as it works. This commit makes everything explicit to remove
such issues.
Fixes#2640
Ref #1373