How to set QWidget background color?

Question

The line w.setBackgroundRole(QPalette.Base) in the code below has no effect. Why? How do I fix that?

import sys
from PySide.QtCore import *
from PySide.QtGui import *

app = QApplication(sys.argv)
w = QWidget()
w.setBackgroundRole(QPalette.Base)
w.show()
app.exec_()

Answer 1

You need to call setAutoFillBackground(True) on the widget. By default, a QWidget doesn't fill its background.

For more information, see the documentation for the setAutoFillBackground property.

If you want to use an arbitrary background color, you need to modify the widget's palette instead:

p = w.palette()
p.setColor(w.backgroundRole(), Qt.red)
w.setPalette(p)