Fix Slider renders track when track colors are transparent - #161814

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  double _value = 0;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: Column(
            spacing: 20,
            mainAxisSize: MainAxisSize.min,
            children: [
              SizedBox(
                height: 4,
                width: 400,
                child: DecoratedBox(
                  decoration: const BoxDecoration(
                    gradient:
                        LinearGradient(colors: [Colors.yellow, Colors.green]),
                  ),
                  child: SliderTheme(
                    data: const SliderThemeData(
                      trackHeight: 200,
                      activeTrackColor: Colors.transparent,
                      inactiveTrackColor: Colors.transparent,
                      padding: EdgeInsets.zero,
                    ),
                    child: Slider(
                      value: _value,
                      max: 100,
                      onChanged: (double value) {
                        setState(() {
                          _value = value;
                        });
                      },
                    ),
                  ),
                ),
              ),
              Text('Slider value: ${_value.roundToDouble()}')
            ],
          ),
        ),
      ),
    );
  }
}