有谁知道PySimpleGUI动态更新input元素的密码字符,点击眼睛显示，再次点击隐藏？

import PySimpleGUI as sg
if __name__ == '__main__':
    layout = [
        [sg.InputText('123456', password_char='*', key='pwd_input'), sg.Button('显示', key='show_pwd')]
    ]
    window = sg.Window('密码框', layout)
    flag = True
    while True:
        event, values = window.read()
        if event in 'show_pwd':
            if flag:
                window.find_element('show_pwd').update('隐藏')
                window.find_element('pwd_input').update(password_char='')
                flag = False
            else:
                window.find_element('show_pwd').update('显示')
                window.find_element('pwd_input').update(password_char='*')
                flag = True