code: function removeChild(child, keepalive) {
           if (this.hasChild(child)) {
             me.utils.function.defer(deferredRemove, this, child, keepalive);
           } else {
             throw new Error("Child is not mine.");
           }
         }
docs: Invokes the removeChildNow in a defer, to ensure the child is removed safely after the update & draw stack has completed
  @name removeChild
  @memberOf me.Container.prototype
  @public
  @function
  @param {me.Renderable} child
  @param {Boolean} [keepalive=False] True to prevent calling child.destroy()