title: Push Async is not supported globally on Android, please use a NavigationPage
body: <p>In <strong>App.xaml.cs</strong> i have following code:</p>
  
  <pre class="lang-cs prettyprint-override"><code>MainPage = new LoginPage();  //LoginPage is ContentPage
  </code></pre>
  
  <p>When user click a <code>Button</code> on that page there is call to <strong>MasterDetailPage</strong> which is of <code>MasterDetailPage</code> type. This will be my real main page from where users will navigate to other pages. I treat it as central place for my application with <code>navigation bar</code>.</p>
  
  <pre class="lang-cs prettyprint-override"><code>Application.Current.MainPage = new MasterDetailPage();
  </code></pre>
  
  <p>being in <strong>MasterDetailPage</strong> in <code>ctor</code> i set default page which open:</p>
  
  <pre class="lang-cs prettyprint-override"><code>Detail = new NavigationPage(new ClientsPage());
  </code></pre>
  
  <p>Now, from here i have a <code>Button</code> to navigate to another <code>ContentPage</code> so when i click a <code>Button</code> this line is executed:</p>
  
  <pre class="lang-cs prettyprint-override"><code>await Application.Current.MainPage.Navigation.PushAsync(new ClientModifyPage(_selectedClient));
  </code></pre>
  
  <p>Nevertheless i am getting following error:</p>
  
  <blockquote>
    <p>PushAsync is not supported globally on Android, please use a NavigationPage</p>
  </blockquote>
  
  <p>What's wrong?</p>