title: How can we know that the screen in touchable in Dart?
body: <p>To develop a responsive application we need to know if the user is using his finger or a mouse  to adapt the behavior of the application. For instance, if the screen is touchable, the buttons will be bigger...</p>
  
  <p>We can listen to <code>Window.onTouch</code> events and <code>Window.onMouse</code> events to guess if the screen is touchable. </p>
  
  <p>But I would like to know it when the application is loading : before any interaction by the user. </p>
  
  <p>How can I do that ?</p>