PyQt5 - QTabBar中缺少关闭按钮图标

from PyQt5.QtWidgets import QApplication, QMainWindow, QTabBar, QStylePainter, QStyleOptionTab, QWidget, QHBoxLayout, QPushButton
from PyQt5.QtCore import Qt

class CloseableTabBar(QTabBar):
    def __init__(self, parent=None):
        super().__init__(parent)
        
    def paintEvent(self, event):
        painter = QStylePainter(self)
        option = QStyleOptionTab()

        for index in range(self.count()):
            self.initStyleOption(option, index)
            painter.drawControl(QStyle.CE_TabBarTabShape, option)
            painter.drawText(option.rect, Qt.AlignCenter, option.text)

            # 绘制关闭按钮图标
            closeButtonRect = self.tabRect(index).adjusted(0, 0, -3, -3)
            closeButton = QPushButton('×', self)
            closeButton.setGeometry(closeButtonRect)
            closeButton.clicked.connect(self.closeTab)

    def closeTab(self):
        sender = self.sender()
        index = self.indexOf(sender)
        self.removeTab(index)

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.tabBar = CloseableTabBar(self)
        self.setTabBar(self.tabBar)

        self.tabWidget = QWidget(self)
        self.tabLayout = QHBoxLayout(self.tabWidget)
        self.tabLayout.addWidget(QWidget())
        self.tabLayout.addWidget(QWidget())
        self.tabLayout.addWidget(QWidget())
        self.setCentralWidget(self.tabWidget)

if __name__ == '__main__':
    app = QApplication([])
    mainWindow = MainWindow()
    mainWindow.show()
    app.exec_()