PyQT5 Moving focus between list boxes using arrow keys

Question

I have a QT widget that has two list boxes that are wrapped in QFrames along with a label and placed side-by-side on QWidget. I can move between them using the tab key but I would like to move between them using the left and right arrow keys. What is the best way to do this?

My QWidget and ListWidgets look like the following

class MainWindow(QWidget):

    def __init__(self):
        super().__init__()

        self.init_ui()

    def init_ui(self):
        hbox = QHBoxLayout()
        hbox.addWidget(Left())
        hbox.addWidget(Right())
        self.setLayout(hbox)
        self.show()


class Left(QFrame):

    def __init__(self):
        super().__init__()

        self.initUI()


    def initUI(self):
        header = QLabel()
        header.setText('Left')

        l = QListWidget()
        items = ['Item %s' % (i + 1) for i in range(10)]
        l.addItems(items)

        vbox = QVBoxLayout()
        vbox.addWidget(header)
        vbox.addWidget(l)

        self.setLayout(vbox)



class Right(QFrame):

    def __init__(self):
        super().__init__()

        self.initUI()

    def initUI(self):
        header = QLabel()
        header.setText('Right')

        l = QListWidget()
        items = ['Item %s' % (i + 1) for i in range(10)]
        l.addItems(items)

        vbox = QVBoxLayout()
        vbox.addWidget(header)
        vbox.addWidget(l)

        self.setLayout(vbox)


def main():
    app = QApplication(sys.argv)
    main_window = MainWindow()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

Answer 1

You can install an event-filter on the list-widgets and then use the focusNextPrevChild method of their parent widget to move the focus:

class MainWindow(QWidget):
    ...
    def init_ui(self):
        hbox = QHBoxLayout()
        self.left = Left()
        self.left.installEventFilter(self)
        hbox.addWidget(self.left)
        self.right = Right()
        self.right.installEventFilter(self)
        hbox.addWidget(self.right)
        self.setLayout(hbox)
        self.show()

    def eventFilter(self, source, event):
        if (event.type() == QEvent.KeyPress and
            (event.key() == Qt.Key_Left or event.key() == Qt.Key_Right) and
            event.modifiers() == Qt.NoModifier and
            (source is self.left or source is self.right)):
            self.focusNextPrevChild(event.key() == Qt.Key_Right)
            return True
        return super(MainWindow, self).eventFilter(source, event)