useStackApproach property
Whether wrapping the widget in a stack is the approach that is goind to be used to render the box. If false, a transparent border is created around the child as a placeholder, and the real border is only displayed when focused is true.
Using the stack approach is recommended for widgets that have a defined size (height and width). You should not use it with widgets that require dragging.
This property is disabled by default on the following widgets:
Implementation
final bool useStackApproach;