Navigation
NavStack
A navigation container rooted at a given view.
NavStack creates a navigation container. Its argument is the root view, a
View or Viewable. Passing nil panics.
The stack owns its own state and is not accessible from outside the
enclosing NavStack subtree; to push or pop from a descendant, use
UseNav.
A NavStack automatically shows a title bar above the current view. Views
contribute title and toolbar content via .NavTitle and .NavToolbar (see
Title and toolbar).