How do I use QT6 Dark Theme with PySide6?

Question

Simple demo application I am trying to set the theme to dark. I would prefer a code version (non QtQuick preferred), but only way I see for Python is with a QtQuick config file, and even that does not work.

from PySide6 import QtWidgets
from PySide6 import QtQuick

if __name__ == '__main__':
    app = QtWidgets.QApplication()
    app.setApplicationDisplayName("Should be Dark Theme")
    app.setStyle("Universal")
    view = QtQuick.QQuickView()
    view.show()
    app.exec()

And I have a qtquickcontrols2.conf configuration file in the same directory. (Also tried setting QT_QUICK_CONTROLS_CONF to absolute path.)

[Controls]
Style=Material

[Universal]
Theme=Dark

[Material]
Theme=Dark

And yet, it's still bright white:

I do not care if it is Material or Universal style, just want some built in dark mode for the title bar. In the end, need a way to make the titlebar dark without creating a custom one.

Thank you for any guidance!

Answer 1

import sys
sys.argv += ['-platform', 'windows:darkmode=2']
app = QApplication(sys.argv)

above 3 lines can change your window to dark mode if you are using windows and Fusion style makes the app more beautiful, tested in windows 10, 11

example:-

from PySide6.QtWidgets import (
    QApplication,
    QCheckBox,
    QComboBox,
    QDateEdit,
    QDateTimeEdit,
    QDial,
    QDoubleSpinBox,
    QFontComboBox,
    QLabel,
    QLCDNumber,
    QLineEdit,
    QMainWindow,
    QProgressBar,
    QPushButton,
    QRadioButton,
    QSlider,
    QSpinBox,
    QTimeEdit,
    QVBoxLayout,
    QWidget,
)
import sys
sys.argv += ['-platform', 'windows:darkmode=2']


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("Widgets App")

        layout = QVBoxLayout()
        widgets = [
            QCheckBox,
            QComboBox,
            QDateEdit,
            QDateTimeEdit,
            QDial,
            QDoubleSpinBox,
            QFontComboBox,
            QLCDNumber,
            QLabel,
            QLineEdit,
            QProgressBar,
            QPushButton,
            QRadioButton,
            QSlider,
            QSpinBox,
            QTimeEdit,
        ]

        for w in widgets:
            layout.addWidget(w())

        widget = QWidget()
        widget.setLayout(layout)

        self.setCentralWidget(widget)


app = QApplication(sys.argv)
app.setStyle('Fusion')
window = MainWindow()
window.show()
app.exec()