floatingActionButton.dart

floatingActionButton: Stack(
          children: <Widget>[
            Align(
              alignment: Alignment.bottomLeft,
              child: FloatingActionButton(
                onPressed: _incrementCounter,
                tooltip: 'Increment',
                child: const Icon(Icons.add),
              ),
            ),
            Align(
              alignment: Alignment.bottomRight,
              child: FloatingActionButton(
                onPressed: _decrementCounter,
                tooltip: 'Decrement',
                child: const Icon(Icons.remove),
              ),
            ),
          ],
        )