Collapse button only shown on hover

Interface looks simpler by defalut. (less things, and the feature is
more likely to be discovered because of “appearing” effect.)

Collapse button is also more noticable when mouse moves over the facet.
Scroll event now works correctly when over facet items

Previously, facet items would grab the event and not scroll the facet.

Scrolling only worked in emoty areas of the facet. It felt buggy.
ListDisplay toggle column + timeline selection line

+ pub demo updates
+ small fixes