Function walk_moved 

fn walk_moved(
    walked: Option<&Vec<ProcessEntry>>,
    snapshot: &ProcessSnapshot,
) -> bool

Whether a walk carries news: the entries the seat’s viewers were last told against the ones this walk found.

None is “nothing ever announced”, not “an empty tree”, so the first walk of a seat that holds nothing still announces.

Equality is over the whole entry, so a merely running tree is news: memory_bytes drifts as processes work, so a held seat with a live tree announces about once per poke rather than only when a process arrives. Narrowing the comparison to ignore the memory figure would freeze the number every viewer draws at whatever the first walk found.