Parent data structure used by parents of slivers that position their children using layout offsets.
This data structure is optimized for fast layout. It is best used by parents that expect to have many children whose relative positions don't change even when the scroll offset does.
) → String
Returns a string representation of this object.
) → void
Called when the RenderObject is removed from the tree.
@mustCallSuper, @protected, inherited
Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed. [...]