diff --git a/lib/screens/currencies_screen.dart b/lib/screens/currencies_screen.dart
index fd2da59..18376df 100644
--- a/lib/screens/currencies_screen.dart
+++ b/lib/screens/currencies_screen.dart
@@ -7,7 +7,7 @@ import '../utils/currencies.dart';
 class CurrenciesScreen extends StatelessWidget {
   final List<Currency> currencies;
 
-  CurrenciesScreen(this.currencies);
+  const CurrenciesScreen(this.currencies, {Key key}) : super(key: key);
 
   Widget _renderItem(BuildContext context, int i) {
     final currency = currencies[i];
@@ -25,7 +25,7 @@ class CurrenciesScreen extends StatelessWidget {
           title: Text(currency.name),
           onTap: () => Navigator.of(context).pop({'code': currency.code}),
         ),
-        Divider(height: 1),
+        const Divider(height: 1),
       ],
     );
   }
@@ -36,7 +36,7 @@ class CurrenciesScreen extends StatelessWidget {
       appBar: PlatformAppBar(
         trailingActions: <Widget>[
           IconButton(
-            icon: Icon(Icons.search),
+            icon: const Icon(Icons.search),
             onPressed: () async {
               Currency result = await showSearch<Currency>(
                 context: context,
@@ -96,7 +96,7 @@ class CurrenciesSearchDelegate extends SearchDelegate<Currency> {
   List<Widget> buildActions(BuildContext context) {
     return [
       IconButton(
-        icon: Icon(Icons.clear),
+        icon: const Icon(Icons.clear),
         onPressed: () {
           query = '';
         },
diff --git a/lib/screens/edit_email.dart b/lib/screens/edit_email.dart
index 62222b7..2e882a5 100644
--- a/lib/screens/edit_email.dart
+++ b/lib/screens/edit_email.dart
@@ -1,10 +1,10 @@
-import 'package:flutter/material.dart';
 import 'package:flutter/cupertino.dart';
-import 'package:provider/provider.dart';
+import 'package:flutter/material.dart';
 import 'package:flutter_platform_widgets/flutter_platform_widgets.dart';
+import 'package:provider/provider.dart';
 
-import '../services/api.dart';
 import '../providers/account.dart';
+import '../services/api.dart';
 
 class EditEmailScreen extends StatefulWidget {
   static const routeName = '/edit-email';
diff --git a/lib/screens/edit_name.dart b/lib/screens/edit_name.dart
index 9125eb6..6251220 100644
--- a/lib/screens/edit_name.dart
+++ b/lib/screens/edit_name.dart
@@ -96,7 +96,7 @@ class _EditNameState extends State<EditNameScreen> {
   Widget build(BuildContext context) {
     return PlatformScaffold(
       appBar: PlatformAppBar(
-        title: Text('Edit Name'),
+        title: const Text('Edit Name'),
         trailingActions: <Widget>[
           PlatformIconButton(
             iosIcon: Icon(CupertinoIcons.check_mark),
@@ -116,7 +116,7 @@ class _EditNameState extends State<EditNameScreen> {
                 controller: _firstNameController,
                 textInputAction: TextInputAction.next,
                 android: (_) => MaterialTextFieldData(
-                  decoration: InputDecoration(
+                  decoration: const InputDecoration(
                     labelText: 'First name',
                   ),
                 ),
@@ -131,7 +131,7 @@ class _EditNameState extends State<EditNameScreen> {
                 controller: _lastNameController,
                 focusNode: _lastNameFocusNode,
                 android: (_) => MaterialTextFieldData(
-                  decoration: InputDecoration(
+                  decoration: const InputDecoration(
                     labelText: 'Last name',
                   ),
                 ),
diff --git a/lib/screens/forgot_password.dart b/lib/screens/forgot_password.dart
index 3272cb0..7886283 100644
--- a/lib/screens/forgot_password.dart
+++ b/lib/screens/forgot_password.dart
@@ -23,7 +23,7 @@ class _ForgotPasswordState extends State<ForgotPasswordScreen> {
         content: Text(message),
         actions: <Widget>[
           PlatformDialogAction(
-            child: Text('OK'),
+            child: const Text('OK'),
             onPressed: () => Navigator.of(context, rootNavigator: true).pop(),
           )
         ],
@@ -59,7 +59,7 @@ class _ForgotPasswordState extends State<ForgotPasswordScreen> {
   Widget build(BuildContext context) {
     return PlatformScaffold(
       appBar: PlatformAppBar(
-        title: Text('Reset password'),
+        title: const Text('Reset password'),
       ),
       body: SafeArea(
         child: SingleChildScrollView(
@@ -70,9 +70,7 @@ class _ForgotPasswordState extends State<ForgotPasswordScreen> {
               Text(
                 'Enter the email address and we’ll send you instructions to reset your password.',
               ),
-              SizedBox(
-                height: 16,
-              ),
+              const SizedBox(height: 16),
               PlatformTextField(
                 autofocus: true,
                 autocorrect: false,
@@ -80,7 +78,7 @@ class _ForgotPasswordState extends State<ForgotPasswordScreen> {
                 keyboardType: TextInputType.emailAddress,
                 textInputAction: TextInputAction.send,
                 android: (_) => MaterialTextFieldData(
-                  decoration: InputDecoration(
+                  decoration: const InputDecoration(
                     labelText: 'Email',
                   ),
                 ),
@@ -89,9 +87,7 @@ class _ForgotPasswordState extends State<ForgotPasswordScreen> {
                 ),
                 onEditingComplete: _resetPassword,
               ),
-              SizedBox(
-                height: 16,
-              ),
+              const SizedBox(height: 16),
               PlatformButton(
                 color: Theme.of(context).primaryColor,
                 android: (_) => MaterialRaisedButtonData(
diff --git a/lib/screens/home.dart b/lib/screens/home.dart
index c1c1bd3..13a463f 100644
--- a/lib/screens/home.dart
+++ b/lib/screens/home.dart
@@ -70,6 +70,25 @@ class _HomeScreenState extends State<HomeScreen> {
 }
 
 class _AndroidHome extends StatelessWidget {
+  final _tabs = <Widget>[
+    Tab(
+      child: Align(
+        alignment: Alignment.center,
+        child: const Text('Balance'),
+      ),
+    ),
+    Tab(
+      child: Align(
+        alignment: Alignment.center,
+        child: const Text('Expenses'),
+      ),
+    ),
+  ];
+  final _tabsViews = [
+    BalanceList(),
+    ExpensesList(),
+  ];
+
   @override
   Widget build(BuildContext context) {
     final ThemeData theme = Theme.of(context);
@@ -125,32 +144,14 @@ class _AndroidHome extends StatelessWidget {
             indicator: TabBarIndicator(
               color: theme.primaryColorLight.withOpacity(0.3),
             ),
-            tabs: <Widget>[
-              Tab(
-                child: Align(
-                  alignment: Alignment.center,
-                  child: Text('Balance'),
-                ),
-              ),
-              Tab(
-                child: Align(
-                  alignment: Alignment.center,
-                  child: Text('Expenses'),
-                ),
-              ),
-            ],
+            tabs: _tabs,
           ),
         ),
-        body: TabBarView(
-          children: <Widget>[
-            BalanceList(),
-            ExpensesList(),
-          ],
-        ),
-        drawer: AppDrawer(),
+        body: TabBarView(children: _tabsViews),
+        drawer: const AppDrawer(),
         floatingActionButton: SpeedDial(
           tooltip: 'Add Expense or Payment',
-          child: Icon(Icons.add),
+          child: const Icon(Icons.add),
           visible: true,
           curve: Curves.decelerate,
           overlayOpacity: theme.brightness == Brightness.dark ? 0.54 : 0.8,
@@ -160,7 +161,7 @@ class _AndroidHome extends StatelessWidget {
             SpeedDialChild(
               child: const Icon(Icons.shopping_basket),
               onTap: () {},
-              labelWidget: SpeedDialLabel(
+              labelWidget: const SpeedDialLabel(
                 title: 'New Expense',
                 subTitle: 'A purchase made for the group',
               ),
@@ -168,7 +169,7 @@ class _AndroidHome extends StatelessWidget {
             SpeedDialChild(
               child: const Icon(Icons.account_balance_wallet),
               onTap: () => {},
-              labelWidget: SpeedDialLabel(
+              labelWidget: const SpeedDialLabel(
                 title: 'New Payment',
                 subTitle: 'Record a payment made in the group',
               ),
diff --git a/lib/screens/login.dart b/lib/screens/login.dart
index 717dfc5..25135b6 100644
--- a/lib/screens/login.dart
+++ b/lib/screens/login.dart
@@ -81,7 +81,7 @@ class _LoginScreenState extends State<LoginScreen> {
   Widget build(BuildContext context) {
     return PlatformScaffold(
       appBar: PlatformAppBar(
-        title: Text('Login'),
+        title: const Text('Login'),
       ),
       body: SafeArea(
         child: SingleChildScrollView(
@@ -96,7 +96,7 @@ class _LoginScreenState extends State<LoginScreen> {
                 keyboardType: TextInputType.emailAddress,
                 textInputAction: TextInputAction.next,
                 android: (_) => MaterialTextFieldData(
-                  decoration: InputDecoration(
+                  decoration: const InputDecoration(
                     labelText: 'Email',
                   ),
                 ),
@@ -113,7 +113,7 @@ class _LoginScreenState extends State<LoginScreen> {
                 controller: _passwordController,
                 textInputAction: TextInputAction.go,
                 android: (_) => MaterialTextFieldData(
-                  decoration: InputDecoration(
+                  decoration: const InputDecoration(
                     labelText: 'Password',
                   ),
                 ),
@@ -123,7 +123,7 @@ class _LoginScreenState extends State<LoginScreen> {
                 focusNode: _passwordFocusNode,
                 onSubmitted: (_) => _handleSubmit(),
               ),
-              SizedBox(height: 16),
+              const SizedBox(height: 16),
               Selector<Auth, bool>(
                 selector: (_, auth) => auth.isFetching,
                 builder: (_, isFetching, __) => PlatformButton(
@@ -137,7 +137,7 @@ class _LoginScreenState extends State<LoginScreen> {
               ),
               PlatformButton(
                 androidFlat: (_) => MaterialFlatButtonData(),
-                child: Text('Forgot password?'),
+                child: const Text('Forgot password?'),
                 onPressed: _forgotPassword,
               ),
             ],
diff --git a/lib/screens/offline.dart b/lib/screens/offline.dart
index 02b5cad..4309c35 100644
--- a/lib/screens/offline.dart
+++ b/lib/screens/offline.dart
@@ -37,6 +37,10 @@ class OfflineScreen extends StatelessWidget {
                     selector: (_, groups) =>
                         Tuple2(groups.status, groups.fetchGroups),
                     builder: (_, data, __) => PlatformButton(
+                      color: Theme.of(context).primaryColor,
+                      android: (_) => MaterialRaisedButtonData(
+                        colorBrightness: Brightness.dark,
+                      ),
                       child: Text('Try again'),
                       onPressed:
                           data.item1 == Status.PENDING ? null : data.item2,
diff --git a/lib/screens/register.dart b/lib/screens/register.dart
index 409af42..220064e 100644
--- a/lib/screens/register.dart
+++ b/lib/screens/register.dart
@@ -91,7 +91,7 @@ class _RegisterScreenState extends State<RegisterScreen> {
   Widget build(BuildContext context) {
     return PlatformScaffold(
       appBar: PlatformAppBar(
-        title: Text('Sign up'),
+        title: const Text('Sign up'),
       ),
       body: SafeArea(
         child: SingleChildScrollView(
@@ -105,7 +105,7 @@ class _RegisterScreenState extends State<RegisterScreen> {
                 keyboardType: TextInputType.text,
                 textInputAction: TextInputAction.next,
                 android: (_) => MaterialTextFieldData(
-                  decoration: InputDecoration(
+                  decoration: const InputDecoration(
                     labelText: 'First name',
                   ),
                 ),
@@ -121,7 +121,7 @@ class _RegisterScreenState extends State<RegisterScreen> {
                 keyboardType: TextInputType.text,
                 textInputAction: TextInputAction.next,
                 android: (_) => MaterialTextFieldData(
-                  decoration: InputDecoration(
+                  decoration: const InputDecoration(
                     labelText: 'Last name',
                   ),
                 ),
@@ -138,7 +138,7 @@ class _RegisterScreenState extends State<RegisterScreen> {
                 keyboardType: TextInputType.emailAddress,
                 textInputAction: TextInputAction.next,
                 android: (_) => MaterialTextFieldData(
-                  decoration: InputDecoration(
+                  decoration: const InputDecoration(
                     labelText: 'Email',
                   ),
                 ),
@@ -155,7 +155,7 @@ class _RegisterScreenState extends State<RegisterScreen> {
                 focusNode: _passwordFocusNode,
                 textInputAction: TextInputAction.go,
                 android: (_) => MaterialTextFieldData(
-                  decoration: InputDecoration(
+                  decoration: const InputDecoration(
                     labelText: 'Password',
                   ),
                 ),
@@ -164,7 +164,7 @@ class _RegisterScreenState extends State<RegisterScreen> {
                 ),
                 onSubmitted: (_) => _handleSubmit(),
               ),
-              SizedBox(height: 16),
+              const SizedBox(height: 16),
               Selector<Auth, bool>(
                 selector: (_, auth) => auth.isFetching,
                 builder: (_, isFetching, __) => PlatformButton(
diff --git a/lib/screens/settings.dart b/lib/screens/settings.dart
index 37c839a..8db058a 100644
--- a/lib/screens/settings.dart
+++ b/lib/screens/settings.dart
@@ -16,6 +16,7 @@ import '../providers/auth.dart';
 import '../providers/account.dart';
 import '../providers/groups.dart';
 import '../widgets/avatar.dart';
+import '../widgets/loading_dialog.dart';
 import '../utils/constants.dart';
 
 enum MoreMenuOptions {
@@ -224,6 +225,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
           PlatformDialogAction(
             onPressed: () => Navigator.of(context).pop(true),
             child: Text('Delete'),
+            ios: (_) => CupertinoDialogActionData(isDestructiveAction: true),
           ),
         ],
       ),
@@ -233,18 +235,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
       showPlatformDialog(
         androidBarrierDismissible: false,
         context: context,
-        builder: (_) => PlatformAlertDialog(
-          content: Column(
-            mainAxisAlignment: MainAxisAlignment.center,
-            crossAxisAlignment: CrossAxisAlignment.center,
-            mainAxisSize: MainAxisSize.min,
-            children: <Widget>[
-              PlatformCircularProgressIndicator(),
-              SizedBox(height: 12),
-              Text('Loading...'),
-            ],
-          ),
-        ),
+        builder: (_) => LoadingDialog(),
       );
       try {
         await Provider.of<AccountProvider>(context, listen: false)
diff --git a/lib/utils/currencies.dart b/lib/utils/currencies.dart
index 52f1316..28ec159 100644
--- a/lib/utils/currencies.dart
+++ b/lib/utils/currencies.dart
@@ -1,8 +1,11 @@
+import 'package:flutter/foundation.dart';
+
+@immutable
 class Currency {
   final String name;
   final String symbol;
   final String code;
-  Currency({this.name, this.symbol, this.code});
+  const Currency({this.name, this.symbol, this.code});
 
   factory Currency.fromMap(Map<String, String> map) => Currency(
         name: map['name'],
@@ -11,7 +14,7 @@ class Currency {
       );
 }
 
-final Map<String, Map<String, String>> currencies = {
+const Map<String, Map<String, String>> currencies = const {
   "AED": {"name": "Emirati Dirham", "code": "AED", "symbol": ".د.ب"},
   "AFN": {"name": "Afghan Afghani", "code": "AFN", "symbol": "؋"},
   "ALL": {"name": "Albanian lek", "code": "ALL", "symbol": "lek"},
diff --git a/lib/widgets/app_drawer.dart b/lib/widgets/app_drawer.dart
index c051973..b7f718e 100644
--- a/lib/widgets/app_drawer.dart
+++ b/lib/widgets/app_drawer.dart
@@ -8,6 +8,8 @@ import '../screens/group.dart';
 import '../screens/settings.dart';
 
 class AppDrawer extends StatefulWidget {
+  const AppDrawer({Key key}) : super(key: key);
+
   @override
   _AppDrawerState createState() => _AppDrawerState();
 }
diff --git a/lib/widgets/empty_expenses.dart b/lib/widgets/empty_expenses.dart
index 490439b..064468b 100644
--- a/lib/widgets/empty_expenses.dart
+++ b/lib/widgets/empty_expenses.dart
@@ -4,6 +4,7 @@ class EmptyExpenses extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return Column(
+      crossAxisAlignment: CrossAxisAlignment.stretch,
       mainAxisAlignment: MainAxisAlignment.center,
       children: <Widget>[
         CircleAvatar(
@@ -20,6 +21,7 @@ class EmptyExpenses extends StatelessWidget {
         Text(
           'No expenses',
           style: Theme.of(context).textTheme.body2.copyWith(fontSize: 18),
+          textAlign: TextAlign.center,
         ),
         const SizedBox(height: 4),
         SizedBox(
diff --git a/lib/widgets/expenses_list.dart b/lib/widgets/expenses_list.dart
index 82822db..e05fb86 100644
--- a/lib/widgets/expenses_list.dart
+++ b/lib/widgets/expenses_list.dart
@@ -5,17 +5,7 @@ import './empty_expenses.dart';
 import '../models/expense.dart';
 
 class ExpensesList extends StatelessWidget {
-  final List<Expense> _expenses = [
-    Expense(
-      id: '1',
-      name: 'Groceries',
-      payerId: '1',
-      date: DateTime.now(),
-      createdAt: DateTime.now(),
-      currency: 'EUR',
-      amount: 10.00,
-    )
-  ];
+  final List<Expense> _expenses = [];
 
   Widget _renderItem(BuildContext context, int i) {
     return Column(
diff --git a/lib/widgets/loading_dialog.dart b/lib/widgets/loading_dialog.dart
new file mode 100644
index 0000000..685ad30
--- /dev/null
+++ b/lib/widgets/loading_dialog.dart
@@ -0,0 +1,20 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_platform_widgets/flutter_platform_widgets.dart';
+
+class LoadingDialog extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return PlatformAlertDialog(
+      content: Column(
+        mainAxisAlignment: MainAxisAlignment.center,
+        crossAxisAlignment: CrossAxisAlignment.center,
+        mainAxisSize: MainAxisSize.min,
+        children: <Widget>[
+          PlatformCircularProgressIndicator(),
+          const SizedBox(height: 12),
+          const Text('Loading...'),
+        ],
+      ),
+    );
+  }
+}
diff --git a/lib/widgets/speed_dial_label.dart b/lib/widgets/speed_dial_label.dart
index c979180..8dcd30c 100644
--- a/lib/widgets/speed_dial_label.dart
+++ b/lib/widgets/speed_dial_label.dart
@@ -4,10 +4,11 @@ class SpeedDialLabel extends StatelessWidget {
   final String title;
   final String subTitle;
 
-  SpeedDialLabel({
+  const SpeedDialLabel({
+    Key key,
     @required this.title,
     @required this.subTitle,
-  });
+  }) : super(key: key);
 
   @override
   Widget build(BuildContext context) {