fix currency selection

lib/base/settings_base_state.dart

@@ -29,7 +29,7 @@ abstract class SettingsBaseState<T extends StatefulWidget> extends BaseState<T>
 
   List<String> getOptions();
 
-  void saveOption();
+  void saveOption(int index);
 
   void getSelectedValue();
 
@@ -42,9 +42,10 @@ abstract class SettingsBaseState<T extends StatefulWidget> extends BaseState<T>
     return new Container(
       height: 56.0,
       child: (new FlatButton(onPressed: () {
+        final int index = getOptions().indexOf(option);
+        saveOption(index);
         setState(() {
-          saveOption();
-          selectedItem = getOptions().indexOf(option);
+          selectedItem = index;
         });
       },
         child: new Row(children: <Widget>[

lib/screens/currencies.dart

@@ -53,7 +53,7 @@ class _CurrenciesState extends SettingsBaseState<CurrenciesScreen> {
   }
 
   @override
-  saveOption() async {
-    await helper.saveCurrency(currencies[selectedItem]);
+  saveOption(int index) async {
+    await helper.saveCurrency(currencies[index]);
   }
 }

lib/screens/languages.dart

@@ -38,9 +38,9 @@ class LanguagesState extends SettingsBaseState<LanguagesScreen> {
   }
 
   @override
-  saveOption() async {
-    await helper.saveLocale(languages[selectedItem]);
-    await StringsLocalization.load(languages[selectedItem]);
+  saveOption(int index) async {
+    await helper.saveLocale(languages[index]);
+    await StringsLocalization.load(languages[index]);
   }
 
   @override