使用元素的方法bind绑定事件'<FocusIn>'生成事件。

import PySimpleGUI as sg

layout = [
    [sg.Input('Initial text', key='IN1')],
    [sg.Input('Initial text', key='IN2')],
    [sg.Button('Go'), sg.Button('Exit')],
]

window = sg.Window('Input auto-clear', layout, use_default_focus=False, finalize=True)
window['IN1'].bind('<FocusIn>', ' FOCUS')

while True:

    event, values = window.read()

    if event in (sg.WIN_CLOSED, 'Exit'):
        break
    elif event == 'IN1 FOCUS':
        window['IN1'].update('')
        window['IN2'].update('')

window.close()