fix(SnackBarTheme): improve SnackBarTheme (#409)

Fixes #408

example/lib/src/controls/buttons.dart

@@ -2,21 +2,9 @@ import 'package:flutter/material.dart';
 import 'package:yaru_example/src/constants.dart';
 import 'package:yaru_icons/yaru_icons.dart';
 
-class Buttons extends StatefulWidget {
+class Buttons extends StatelessWidget {
   const Buttons({super.key});
 
-  @override
-  State<Buttons> createState() => _ButtonsState();
-}
-
-class _ButtonsState extends State<Buttons> {
-  void incrementCounter() {
-    setState(() {
-      ScaffoldMessenger.of(context)
-          .showSnackBar(const SnackBar(content: Text('Yay! ❤️ for Yaru')));
-    });
-  }
-
   @override
   Widget build(BuildContext context) {
     const icon = Icon(YaruIcons.notification_filled);

example/lib/src/controls/fabs.dart

@@ -1,14 +1,14 @@
 import 'package:flutter/material.dart';
 import 'package:yaru_example/src/constants.dart';
+import 'package:yaru_example/src/utils.dart';
 import 'package:yaru_icons/yaru_icons.dart';
 
 class Fabs extends StatelessWidget {
   const Fabs({super.key});
 
   @override
   Widget build(BuildContext context) {
-    void onPressed() => ScaffoldMessenger.of(context)
-        .showSnackBar(const SnackBar(content: Text('Yay! ❤️ for Yaru')));
+    void onPressed() => showSnack(context);
 
     return Wrap(
       spacing: kWrapSpacing,

example/lib/src/home/home_page.dart

@@ -8,6 +8,7 @@ import 'package:yaru_example/src/controls/controls_view.dart';
 import 'package:yaru_example/src/fonts/fonts_view.dart';
 import 'package:yaru_example/src/home/color_disk.dart';
 import 'package:yaru_example/src/textfields/text_fields_view.dart';
+import 'package:yaru_example/src/utils.dart';
 import 'package:yaru_icons/yaru_icons.dart';
 
 final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey();
@@ -78,9 +79,13 @@ class HomePageState extends State<HomePage> {
           ),
         ),
         title: const _Title(),
-        actions: const [
-          Padding(
-            padding: EdgeInsets.only(right: kWrapSpacing),
+        actions: [
+          IconButton(
+            onPressed: () => showSnack(context),
+            icon: const Icon(YaruIcons.plus),
+          ),
+          const Padding(
+            padding: EdgeInsets.symmetric(horizontal: kWrapSpacing),
             child: _ThemeButton(),
           ),
         ],

example/lib/src/utils.dart

@@ -0,0 +1,15 @@
+import 'package:flutter/material.dart';
+
+ScaffoldFeatureController<SnackBar, SnackBarClosedReason> showSnack(
+  BuildContext context,
+) {
+  return ScaffoldMessenger.of(context).showSnackBar(
+    SnackBar(
+      content: const Text('Yay! ❤️ for Yaru'),
+      action: SnackBarAction(
+        label: 'Ok',
+        onPressed: () {},
+      ),
+    ),
+  );
+}

lib/src/themes/common_themes.dart

@@ -590,14 +590,11 @@ DrawerThemeData _createDrawerTheme(ColorScheme colorScheme) {
 SnackBarThemeData _createSnackBarTheme(ColorScheme colorScheme) {
   const fg = Colors.white;
   return SnackBarThemeData(
-    width: kSnackBarWidth,
-    backgroundColor: const Color.fromARGB(255, 20, 20, 20).withOpacity(0.95),
+    backgroundColor: const Color.fromARGB(250, 20, 20, 20),
     closeIconColor: fg,
-    actionTextColor: Colors.white,
+    actionTextColor: colorScheme.primary,
     contentTextStyle: const TextStyle(color: fg),
-    actionBackgroundColor: Colors.transparent,
     disabledActionTextColor: fg.withOpacity(0.7),
-    disabledActionBackgroundColor: Colors.transparent,
     behavior: SnackBarBehavior.floating,
     elevation: 0,
     shape: RoundedRectangleBorder(