onMouseDown property Null safety

EventStream<MouseEvent> onMouseDown

Dispatched when a user presses the pointing device button over an InteractiveObject instance.

If the target is a SimpleButton instance, the SimpleButton instance displays the downState display object as the default behavior. If the target is a selectable text field, the text field begins selection as the default behavior.

Implementation

EventStream<MouseEvent> get onMouseDown =>
    InteractiveObject.mouseDownEvent.forTarget(this);