Moved calls to super.initState() to the top of overrides to conform with documented method contract (#326)

Author: raja-s

README.md

@@ -193,8 +193,8 @@ class HomePage extends StatefulWidget {
 class _HomePageState extends State<HomePage> with WindowListener {
   @override
   void initState() {
-    windowManager.addListener(this);
     super.initState();
+    windowManager.addListener(this);
   }
 
   @override
@@ -305,9 +305,9 @@ class HomePage extends StatefulWidget {
 class _HomePageState extends State<HomePage> with WindowListener {
   @override
   void initState() {
+    super.initState();
     windowManager.addListener(this);
     _init();
-    super.initState();
   }
 
   @override
@@ -466,8 +466,8 @@ class HomePage extends StatefulWidget {
 class _HomePageState extends State<HomePage> with WindowListener {
   @override
   void initState() {
-    windowManager.addListener(this);
     super.initState();
+    windowManager.addListener(this);
   }
 
   @override