I want to show a dialog from root widget (the one that created MaterialApp) I have a `NavigatorState` instance, but showDialog requires context that would return `Navigator.of(context)`. 

It looks like I need to provide context from a route, but I can't do this, because the root widget does not have it.

EDIT: I have found a workaround: I can push fake route that is only there to showDialog and then pop that route when dialog finishes. Not pretty but works.