html">addRetained</a> all descendant layers are also
considered as used in this scene. The same single-usage restriction
applies to descendants.</p>
<p>When a layer is passed as an <code>oldLayer</code> argument to a push method, it may
no longer be used in subsequent frames. If you would like to continue
reusing the resources associated with the layer, store the layer object
returned by the push method and use that in the next frame instead of the
original object.</p>
<p>See <a href="dart-ui/SceneBuilder/p