Fired when a pending mapping-key sequence is dropped before completing:
its timer expired, CompositionEngine#abort was called, or
CompositionEngine#undo cancelled it.
No target key has executed at this point, so there is nothing to undo —
this event exists so subscribers can clear a "waiting for the next key"
state. Without it, a timeout is indistinguishable from a sequence that
is still in progress.
Fired when a pending mapping-key sequence is dropped before completing: its timer expired, CompositionEngine#abort was called, or CompositionEngine#undo cancelled it.
No target key has executed at this point, so there is nothing to undo — this event exists so subscribers can clear a "waiting for the next key" state. Without it, a timeout is indistinguishable from a sequence that is still in progress.