code: func (g *Gui) SetManager(managers ...Manager) {
  	g.managers = managers
  	g.currentView = nil
  	g.views = nil
  	g.keybindings = nil
  
  	go func() { g.tbEvents <- termbox.Event{Type: termbox.EventResize} }()
  }
docs: // SetManager sets the given GUI managers. It deletes all views and
  // keybindings.