How to create a new window button PySide/PyQt?

Question

I\'m having problems with a \"New Window\" function in PyQt4/PySide with Python 2.7. I connected a initNewWindow() function, to create a new window, to an actio

Answer 1

When initNewWindow() returns, the window variable is deleted and the window's reference count drops to zero, causing the newly created C++ object to be deleted. This is why your window closes immediately.

If you want to keep it open, make sure to keep a reference around. The easiest way to do this is to make your new window a child of the calling window, and set its WA_DeleteOnClose widget attribute (see Qt::WidgetAttribute).

Answer 2

If a function creates a PyQt object that the application needs to continue using, you will have to ensure that a reference to it is kept somehow. Otherwise, it could be deleted by the Python garbage collector immediately after the function returns.

So either give the object a parent, or keep it as an attribute of some other object. (In principle, the object could also be made a global variable, but that is usually considered bad practice).

Here's a revised version of your example script that demonstrates how to fix your problem:

from PySide import QtGui, QtCore

class Window(QtGui.QMainWindow):
    def __init__(self):
        QtGui.QMainWindow.__init__(self)
        menu = self.menuBar().addMenu(self.tr('View'))
        action = menu.addAction(self.tr('New Window'))
        action.triggered.connect(self.handleNewWindow)

    def handleNewWindow(self):
        window = QtGui.QMainWindow(self)
        window.setAttribute(QtCore.Qt.WA_DeleteOnClose)
        window.setWindowTitle(self.tr('New Window'))
        window.show()
        # or, alternatively
        # self.window = QtGui.QMainWindow()
        # self.window.setWindowTitle(self.tr('New Window'))
        # self.window.show()

if __name__ == '__main__':

    import sys
    app = QtGui.QApplication(sys.argv)
    window = Window()
    window.resize(300, 300)
    window.show()
    sys.exit(app.exec_())