Widgets style is not the same as my system's style

[Oskar der Grosse]

Hi, i'm trying to create an app for linux desktop and chose QtWidgets for it. In QtDesigner, widgets look how they should be which is Lightly i'm currently using. But when i try to preview GUI from terminal using "python main.py", widgets are not looking like my system's style. I use KDE Plasma and have another styles too like Breeze and Oxygen. I see only two styles, Windows and Fusion as a result of print(QStyleFactory.keys()). But QtDesigner knows what styles i have and presents me all of styles i have like Breeze Style, Windows Style, Fusion Style, Lightly Style. I'm trying to make widgets look like system's default style do you know how do i do it?
This is the preview from QtDesigner:

And this is the output from "python main.py"

The codes in main.py are:

import sys
from PySide6.QtWidgets import *
from PySide6.QtCore import QFile
from ui_mainwindow import Ui_MainWindow
from qtstyles import StylePicker

print(QStyleFactory.keys())

class MainWindow(QMainWindow):
    def __init__(self):
        super(MainWindow, self).__init__()
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    app.setStyle('Lightly')
  # app.setStyle("Default')
  # app.setStyle("Breeze')
    window = MainWindow()
    window.show()

    sys.exit(app.exec())

[SGaist]

Hi and welcome to devnet,

Is it a pip installed PySide6 ?

If so, it likely does not look into your system as it does not use your distribution provided Qt.

[Oskar der Grosse]

@SGaist I uninstalled the PySide6 with doing "pip uninstall PySide6" and installed from my distribution's repositories but this didn't work. I also redone "uic -g python mainwindow.ui > ui_mainwindow.py", nothing changed, i still see Windows and Fusion as a result of print(QStyleFactory.keys()).
My project folder is located in my Documents folder, should i move project folder somewhere else?

[SGaist]

Can you start your script with the QT_DEBUG_PLUGINS environment variable set to 1 ?

This is to see what happens on the plugin side.

[Oskar der Grosse]

@SGaist Setting QT_DEBUG_PLUGINS environment variable to 1 did show nothing to me or i was looking wrong place, i'm a bit cursed at things like this. But thank you so much for taking the time for me. I tried using PyQt5 instead of PySide6 and this worked pretty good. Now i can see every styles that my system has and the GUI is just looks like native. Thank you again.

[SGaist]

Which distribution are you using ?

Wait... I just realized, PySide6 uses Qt 6 however your system is likely still on Qt 5 hence your issue.

Would you mind trying PySide2 ? I guess it should work as well as PyQt5 in that regard.

[Oskar der Grosse]

@SGaist im having an another error which is "ImportError: libshiboken2.abi3.so.5.15: cannot open shared object file: No such file or directory" so i didnt even give it a try
i use manjaro kde

[SGaist]

With PySide2 ?
How did you install it ?

[Oskar der Grosse]

@SGaist i have installed it with pip now installed from my distribution's repositories i dont get that error anymore but widgets styles are still fusion

[SGaist]

Even if you use a different style explicitly ?