What a filter pass concluded. With no filter in force the three sets still hold every node of their type, so style and layout passes never need an "is a filter on" branch.
Matched nodes of a still-drawn type. Zero on a non-empty library is the "no matches" state.
Node types a Visibility checkbox switched off: not drawn at all.
What a filter pass concluded. With no filter in force the three sets still hold every node of their type, so style and layout passes never need an "is a filter on" branch.