请考虑以下代码。我在BeagleBone上运行它（libqt5widgets5：armhf 5.7.1 + dfsg-3 + b1）。它会触发FocusInEvent事件。当我在行（***）中用QWidget替换QDialog时，它会停止工作。为什么呢？
对于不同的PyQt5安装，这是不可重现的（我使用Cygwin进行检查）。
[1]这可能与:focus don't work in PyQt (QT 5.7)有关，也可能与之无关 [2]在C ++中同样的事情也不起作用，https://github.com/leshikus/qt-test
#!/usr/bin/python3
# -*- coding: utf-8 -*-
import sys
from PyQt5.QtWidgets import QApplication, QWidget, QSlider, QCheckBox, QVBoxLayout, QMainWindow, QDialog
from PyQt5.QtCore import Qt, QEvent
class MyWidget(QSlider):
def __init__(self):
super().__init__()
def focusInEvent(self, event):
super().focusInEvent(event)
print('focusInEvent')
def focusOutEvent(self, event):
super().focusOutEvent(event)
print('focusOutEvent')
def eventFilter(self, source, event):
print("eventFilter", event.type(), source)
return super().eventFilter(source, event)
if __name__ == '__main__':
app = QApplication(sys.argv)
w = QDialog() # got replaced with QWidget (***)
w.resize(300, 200)
w.move(30, 30)
layout = QVBoxLayout()
layout.setContentsMargins(0, 0, 0, 0)
layout.setSpacing(0)
s = MyWidget()
layout.addWidget(s)
w.setLayout(layout)
s.installEventFilter(s)
s.setFocus()
w.show()
sys.exit(app.exec_())