isPositioned property

bool isPositioned

Whether this child is considered positioned.

A child is positioned if any of the top, right, bottom, or left properties are non-null. Positioned children do not factor into determining the size of the stack but are instead placed relative to the non-positioned children in the stack.

Implementation 

bool get isPositioned => top != null || right != null || bottom != null || left != null || width != null || height != null;