Fix deprecations and code style

lib/main.dart

@@ -1,4 +1,5 @@
 import 'dart:io';
+
 import 'package:flutter/material.dart';
 import 'package:package_info_plus/package_info_plus.dart';
 import 'package:provider/provider.dart';

lib/src/pages/downloader_page.dart

@@ -13,8 +13,8 @@ class DownloaderPage extends StatelessWidget {
       appBar: AppBar(
         title: Text(context.t('Downloader')),
       ),
-      body: Column(
-        children: const [
+      body: const Column(
+        children: [
           Logo(),
           DownloaderMenu(),
         ],

lib/src/pages/main_page.dart

@@ -28,8 +28,8 @@ class _MainPageState extends State<MainPage> {
         title: Text(context.t('Main menu')),
       ),
       drawer: const LeftMenu(),
-      body: Column(
-        children: const [
+      body: const Column(
+        children: [
           Logo(),
           MainMenu(),
         ],

lib/src/pages/manager.dart

@@ -138,10 +138,10 @@ class _ManagerState extends State<Manager> with PreferencesMixin {
       if ((entity.path.endsWith('.conf')) && (_isValidConf(entity.path))) {
         String name = path.basenameWithoutExtension(entity.path);
         currentVms.add(name);
-        File pidFile = File(name + '/' + name + '.pid');
+        File pidFile = File('$name/$name.pid');
         if (pidFile.existsSync()) {
           String pid = pidFile.readAsStringSync().trim();
-          Directory procDir = Directory('/proc/' + pid);
+          Directory procDir = Directory('/proc/$pid');
           if (procDir.existsSync()) {
             if (_activeVms.containsKey(name)) {
               activeVms[name] = _activeVms[name]!;
@@ -172,11 +172,11 @@ class _ManagerState extends State<Manager> with PreferencesMixin {
   }
 
   Widget _buildVmList() {
-    List<Widget> _widgetList = [];
+    List<Widget> widgetList = [];
     final Color buttonColor = Theme.of(context).brightness == Brightness.dark
         ? Colors.white70
         : Theme.of(context).colorScheme.primary;
-    _widgetList.addAll(
+    widgetList.addAll(
       [
         Padding(
           padding: const EdgeInsets.symmetric(vertical: 16.0),
@@ -222,12 +222,12 @@ class _ManagerState extends State<Manager> with PreferencesMixin {
       return _buildRow(vm, buttonColor);
     }).toList();
     for (var row in rows) {
-      _widgetList.addAll(row);
+      widgetList.addAll(row);
     }
 
     return ListView(
       padding: const EdgeInsets.all(16.0),
-      children: _widgetList,
+      children: widgetList,
     );
   }
 
@@ -239,10 +239,10 @@ class _ManagerState extends State<Manager> with PreferencesMixin {
     if (active) {
       vmInfo = _activeVms[currentVm]!;
       if (vmInfo.spicePort != null) {
-        connectInfo += context.t('SPICE port') + ': ' + vmInfo.spicePort! + ' ';
+        connectInfo += '${context.t('SPICE port')}: ${vmInfo.spicePort!} ';
       }
       if (vmInfo.sshPort != null && _terminalEmulator != null) {
-        connectInfo += context.t('SSH port') + ': ' + vmInfo.sshPort! + ' ';
+        connectInfo += '${context.t('SSH port')}: ${vmInfo.sshPort!} ';
         _detectSsh(int.parse(vmInfo.sshPort!)).then((sshRunning) {
           if (sshRunning && !sshy) {
             setState(() {
@@ -331,12 +331,8 @@ class _ManagerState extends State<Manager> with PreferencesMixin {
                         showDialog<String?>(
                           context: context,
                           builder: (BuildContext context) => AlertDialog(
-                            title: Text('Delete ' + currentVm),
-                            content: Text('You are about to delete ' +
-                                currentVm +
-                                '. This cannot be undone. ' +
-                                'Would you like to delete the disk image but keep the ' +
-                                'configuration, or delete the whole VM?'),
+                            title: Text('Delete $currentVm'),
+                            content: Text('You are about to delete $currentVm. This cannot be undone. Would you like to delete the disk image but keep the configuration, or delete the whole VM?'),
                             actions: [
                               TextButton(
                                 child: const Text('Cancel'),
@@ -390,21 +386,22 @@ class _ManagerState extends State<Manager> with PreferencesMixin {
               IconButton(
                 icon: SvgPicture.asset('assets/images/console.svg',
                     semanticsLabel: 'Connect with SSH',
-                    color: sshy ? buttonColor : Colors.grey),
+                    colorFilter: ColorFilter.mode(sshy ? buttonColor : Colors.grey, BlendMode.srcIn)
+                ),
                 tooltip: sshy
                     ? 'Connect with SSH'
                     : 'SSH server not detected on guest',
                 onPressed: !sshy
                     ? null
                     : () {
-                        TextEditingController _usernameController =
+                        TextEditingController usernameController =
                             TextEditingController();
                         showDialog<bool>(
                           context: context,
                           builder: (BuildContext context) => AlertDialog(
                             title: Text('Launch SSH connection to $currentVm'),
                             content: TextField(
-                              controller: _usernameController,
+                              controller: usernameController,
                               decoration: const InputDecoration(
                                   hintText: "SSH username"),
                             ),
@@ -426,7 +423,7 @@ class _ManagerState extends State<Manager> with PreferencesMixin {
                               'ssh',
                               '-p',
                               vmInfo.sshPort!,
-                              _usernameController.text + '@localhost'
+                              '${usernameController.text}@localhost'
                             ];
                             // Set the arguments to execute the ssh command in the default terminal.
                             // Strip the extension as x-terminal-emulator may point to a .wrapper

lib/src/widgets/home_page/downloader_menu.dart

@@ -72,12 +72,12 @@ class _DownloaderMenuState extends State<DownloaderMenu> with PreferencesMixin {
             const Divider(
               thickness: 2,
             ),
-            Row(
+            const Row(
               children: [
                 Expanded(
                   child: Column(
                     mainAxisAlignment: MainAxisAlignment.start,
-                    children: const [
+                    children: [
                       Padding(
                         padding: EdgeInsets.symmetric(horizontal: 12),
                         child: HomePageButtonGroup(),

lib/src/widgets/home_page/home_page_button_group.dart

@@ -105,8 +105,8 @@ class _HomePageButtonGroupState extends State<HomePageButtonGroup> {
     showDialog(
       context: context,
       barrierDismissible: false,
-      builder: (context) => WillPopScope(
-        onWillPop: () async => false,
+      builder: (context) => PopScope(
+        canPop: false,
         child: AlertDialog(
           shape: const RoundedRectangleBorder(
             borderRadius: BorderRadius.all(Radius.circular(8.0)),
@@ -153,8 +153,8 @@ class _HomePageButtonGroupState extends State<HomePageButtonGroup> {
     showDialog(
       context: context,
       barrierDismissible: false,
-      builder: (context) => WillPopScope(
-        onWillPop: () async => false,
+      builder: (context) => PopScope(
+        canPop: false,
         child: AlertDialog(
           shape: const RoundedRectangleBorder(
             borderRadius: BorderRadius.all(Radius.circular(8.0)),