on_descendant_focus(
self,
event: events.DescendantFocus,
) -> NoneKeep the active-question highlight in sync with focus.
A mouse click moves focus into another question's text input, or onto
the question container itself for choice-based questions (whose options
are not individually focusable), without going through
_set_active_question, which would otherwise leave the highlight on
the previously active question. Sync the highlight to the focused
question so exactly one question is ever active. Focus is not moved
here, so the widget the user clicked keeps focus.