title: App is confusing between application orientation
body: <p>I applied <code>SystemChrome.setPreferredOrientations([DeviceOrientation.portraitDown]);</code> to my second page of application when I click on button to go new screen where I set portrait orientation my application firstly show in portrait orientation and change its orientation for 1 second to landscape and after 1 second it set back to portrait. I am calling <code>SystemChrome.setPreferredOrientations([DeviceOrientation.portraitDown]);</code> in <code>build</code> function for each class.</p>