allowImplicitScrolling property

bool allowImplicitScrolling

Whether a viewport is allowed to change its scroll position implicitly in responds to a call to RenderObject.showOnScreen.

RenderObject.showOnScreen is for example used to bring a text field fully on screen after it has received focus. This property controls whether the viewport associated with this object is allowed to change the scroll position to fulfill such a request.

Implementation 

bool get allowImplicitScrolling => true;