title: Flutter - Show hide widgets in Stack without reloading the whole Scaffold with setState (Stack with GoogleMap like Uber)
body: <p>I have a Stack where a GoogleMap is the first item.</p>
  
  <p>I have some Containers afterwards, similar to Uber. I would like to show hide widgets, but without reloading the whole scaffold. Any tips on best to achieve it?
  I am having some success with StreamBuilder, but failing with using streams as broadcast for some reason.</p>