Indicates whether an event is a bubbling event. If the event can bubble, this value is true; otherwise it is false.
When an event occurs, it moves through the three phases of the event flow: the capture phase, which flows from the top of the display list hierarchy to the node just before the target node; the target phase, which comprises the target node; and the bubbling phase, which flows from the node subsequent to the target node back up the display list hierarchy.
Source
bool get bubbles => _bubbles;