open new window in pyqt5

1from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton, QLabel, QVBoxLayout, QWidget
2
3import sys
4
5
6class AnotherWindow(QWidget):
7    """
8    This "window" is a QWidget. If it has no parent, it
9    will appear as a free-floating window as we want.
10    """
11    def __init__(self):
12        super().__init__()
13        layout = QVBoxLayout()
14        self.label = QLabel("Another Window")
15        layout.addWidget(self.label)
16        self.setLayout(layout)
17
18
19class MainWindow(QMainWindow):
20
21    def __init__(self):
22        super().__init__()
23        self.button = QPushButton("Push for Window")
24        self.button.clicked.connect(self.show_new_window)
25        self.setCentralWidget(self.button)
26
27    def show_new_window(self, checked):
28        w = AnotherWindow()
29        w.show()
30
31
32app = QApplication(sys.argv)
33w = MainWindow()
34w.show()
35app.exec_()
36

1from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton, QLabel, QVBoxLayout, QWidget
2
3import sys
4
5from random import randint
6
7
8class AnotherWindow(QWidget):
9    """
10    This "window" is a QWidget. If it has no parent, it
11    will appear as a free-floating window as we want.
12    """
13    def __init__(self):
14        super().__init__()
15        layout = QVBoxLayout()
16        self.label = QLabel("Another Window % d" % randint(0,100))
17        layout.addWidget(self.label)
18        self.setLayout(layout)
19
20
21class MainWindow(QMainWindow):
22
23    def __init__(self):
24        super().__init__()
25        self.w = None  # No external window yet.
26        self.button = QPushButton("Push for Window")
27        self.button.clicked.connect(self.show_new_window)
28        self.setCentralWidget(self.button)
29
30    def show_new_window(self, checked):
31        if self.w is None:
32            self.w = AnotherWindow()
33            self.w.show()
34
35        else:
36            self.w.close()  # Close window.
37            self.w = None  # Discard reference.
38
39
40app = QApplication(sys.argv)
41w = MainWindow()
42w.show()
43app.exec_()
44