OnBoarding: The back button should not result in the app quitting

lib/screens/onboarding_screens.dart

@@ -183,7 +183,7 @@ class OnBoardingScreenState extends State<OnBoardingScreen> {
       },
     );
 
-    return new Scaffold(
+    var scaffold = new Scaffold(
       key: _scaffoldKey,
       body: new Container(
         width: double.infinity,
@@ -202,6 +202,20 @@ class OnBoardingScreenState extends State<OnBoardingScreen> {
         padding: EdgeInsets.all(16.0),
       ),
     );
+
+    return new WillPopScope(
+      onWillPop: () {
+        if (_currentPageIndex != 0) {
+          pageController.previousPage(
+            duration: Duration(milliseconds: 200),
+            curve: Curves.easeIn,
+          );
+        } else {
+          SystemChannels.platform.invokeMethod('SystemNavigator.pop');
+        }
+      },
+      child: scaffold,
+    );
   }
 
   void setPageInputUrlDone() {

pubspec.yaml

@@ -1,6 +1,6 @@
 name: journal
 description: A Journaling App Built on top of Git
-version: 1.0.0+3
+version: 1.0.0+5
 
 dependencies:
   flutter: