How to change color of QMainWindow borders and title bar?

Question

The QMainWindow below is assigned a dark-gray background-color using QSS. I would also like to change the color of the borders and the color of the title bar.

How to achieve control of the appearance of the QMainWindow borders and titlebar?

I would like to know how to change their colors and how to control the borders width and the title-bar's height.

from PyQt4.QtCore import *
from PyQt4.QtGui import *

appStyle="""
QMainWindow{
background-color: darkgray;
}
"""

class GUI(QMainWindow):
    def __init__(self):
        super(GUI, self).__init__()  
        self.setStyleSheet(appStyle)

if __name__ == '__main__': 
    if not QApplication.instance(): app=QApplication([])
    w=GUI() 
    w.setStyleSheet(appStyle)
    w.show() 
    w.raise_()

    sys.exit(app.exec_())

Answer 1

This can be implemented in QT C++ by detecting current system theme from Windows registry and applying the Dark Window hints. A dark style in addition to this can make dark light window modes.

A sample project demonstrating this is shared here if it helps to adapt

https://envyen.com/posts/2021-10-24-QT-Windows-Dark-theme/