Event name (must be a key of GeoLeafEventMap).
Typed payload for the event.
false when a listener called preventDefault(); true otherwise — including
when document is unavailable or the dispatch itself failed, so that the default action
still happens.
Dispatches a typed GeoLeaf event that listeners may CANCEL, and reports whether one did.
Same sanitised copy as dispatchGeoLeafEvent; the only differences are
cancelable: trueand the returned verdict. It exists for the events whose default action is a piece of interface a host may want to replace — the boot failure screen.