PyQt4: Difference between QWidget and QMainWindow

Question

When reading through a PyQt4 tutorial, sometimes the examples uses QtGui.QMainWindow, sometimes it uses QtGui.QWidget.

Question: How do you tell when to use which?

import sys
from PyQt4 import QtGui


class Example(QtGui.QMainWindow):

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

        self.initUI()

    def initUI(self):               

        self.statusBar().showMessage('Ready')

        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('Statusbar')    
        self.show()


def main():

    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

Another code example:

import sys
from PyQt4 import QtGui, QtCore

class Example(QtGui.QWidget):

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

        self.initUI()

    def initUI(self):      

        cb = QtGui.QCheckBox('Show title', self)
        cb.move(20, 20)
        cb.toggle()
        cb.stateChanged.connect(self.changeTitle)

        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('QtGui.QCheckBox')
        self.show()

    def changeTitle(self, state):

        if state == QtCore.Qt.Checked:
            self.setWindowTitle('QtGui.QCheckBox')
        else:
            self.setWindowTitle('')

def main():

    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

possible duplicate of [What's the difference between QMainWindow, QWidget and QDialog?](http://stackoverflow.com/questions/3298792/whats-the-difference-between-qmainwindow-qwidget-and-qdialog) — nbro, Jun 30 '15 at 01:35

score 20 · Accepted Answer · edited Jun 30 '15 at 01:35

20

QMainWindow is a class that understands GUI elements like a

toolbar,
statusbar,
central widget,
docking areas.

QWidget is just a raw widget.

When you want to have a main window for you project, use QMainWindow.

If you want to create a dialog box (modal dialog), use QWidget, or, more preferably, QDialog.

edited Jun 30 '15 at 01:35

nbro

15,395
32
113
196

answered Sep 19 '13 at 15:17

antonone

2,045
1
25
35

score 5 · Answer 2 · answered Sep 19 '13 at 18:29

5

If you are not going to use a menu bar, tool bar or dock widgets, they are the same to you. If you will use one of those, use QMainWindow. And don't forget to call setCentralWidget to your main layout widget.

answered Sep 19 '13 at 18:29

MadeOfAir

2,933
5
31
39

PyQt4: Difference between QWidget and QMainWindow

2 Answers2