This is a simplest app to handle touch input.
It can be run in session:
ffx session start ffx session add fuchsia-pkg://fuchsia.com/flatland-examples#meta/simplest-app-flatland-session.cm
simplest-app-flatland-session.cml will pass view_provider argument to the app. Then the app will setup fuchsia.ui.app.ViewProvider service, and ignore fuchsia.element.GraphicalPresenter setup.
It can be also run with component:
ffx component run <NAME> fuchsia-pkg://fuchsia.com/flatland-examples#meta/simplest-app-flatland.cm
simplest-app-flatland.cml will pass graphical_presenter argument to the app.