如何在PyQt5中使`textEdit.find()`的选定文本变暗？

from PyQt5.QtWidgets import QApplication, QMainWindow, QTextEdit
from PyQt5.QtGui import QTextCursor, QTextCharFormat, QColor

if __name__ == '__main__':
    app = QApplication([])
    window = QMainWindow()
    
    textEdit = QTextEdit(window)
    textEdit.setText("Hello World")
    
    cursor = textEdit.textCursor()
    cursor.select(QTextCursor.WordUnderCursor)  # 选择要变暗的文本
    
    # 创建一个格式对象并设置其颜色为暗色
    charFormat = QTextCharFormat()
    charFormat.setForeground(QColor(100, 100, 100))  # 设置颜色为暗色
    
    cursor.setCharFormat(charFormat)  # 应用格式
    
    window.show()
    app.exec_()