message: Clarify that the object's mask must be in the subtree of its parent in the docs
diff: @@ -936,7 +936,9 @@ export abstract class DisplayObject extends EventEmitter
  * Sets a mask for the displayObject. A mask is an object that limits the visibility of an
  * object to the shape of the mask applied to it. In PixiJS a regular mask must be a
  * {@link PIXI.Graphics} or a {@link PIXI.Sprite} object. This allows for much faster masking in canvas as it
  - * utilities shape clipping. To remove a mask, set this property to `null`.
  + * utilities shape clipping. Furthermore, a mask of an object must be in the subtree of its parent.
  + * Otherwise, `getLocalBounds` may calculate incorrect bounds, which makes the container's width and height wrong.
  + * To remove a mask, set this property to `null`.
  *
  * For sprite mask both alpha and red channel are used. Black mask is the same as transparent mask.
  * @example
  