isZombieWidget() {

    return this.domNode.isTiddlyWikiFakeDom === true
           || !this.document.body.contains(this.getContainer());

  }
A zombie widget is a widget that is removed from the dom tree
but still referenced or still partly executed -- I mean
otherwise you couldn't call this function, right?

If TiddlyMap is executed in a fake environment, the function
always returns true.