title: How to overload sizehint() method of QMainWindow's layout
body: <p>I want to make a main window application in PyQt that its size is fixed.</p>
  
  <p>I tried to find a way how to overload sizehint() method of the QMainWindow's layout in order to set the size returned by sizeHint() but didn't know how to do it.</p>
  
  <p>After some researching i have learned that i can set the size of a QMainWindow with QWidget's function setFixedSize(QSize).<br></p>
  
  <p>But still i'm curious how it can be done the other way.</p>
  
  <p>It could be a lack of knowledge in Python programming.</p>