How to call one mainwindow to another mainwindow in Qt (or PyQt)

[arjunjain]

In my project i have created two mainwindow i want to call mainwindow2 from the mainwindow1 (which in running). in mainwindow1 i am already used the app.exec_() (PyQt) and to show maindow2 i am using the maindow2.show() in the click event of the button but does not show anything