title: How to change the window title in pyside?
body: <p>I have read the documentation on the following matter, but <code>Qt</code> is so overwhelmingly complex I might have missed the piece. </p>
  
  <p>I have created a <code>QMainWindow</code> and set a title using <code>self.setWindowTitle</code>. Later in the code I want to simply change this title and so I used the method <code>self.setWindowTitle</code> again. But this only removed the title from my application, but put the correct title  on the panel in Ubuntu. </p>
  
  <p>Further explanation on an Ubuntu system: For example, When I edit this text in the webbrowser window the title says 'How to change the window...' and on the panel on the top of the computer screen I see the text 'Firefox Web Browser'. </p>
  
  <p>My <code>pyside</code> Qt example now removes the title from the application window and puts it instead on the upper hand panel. </p>
  
  <p>Do I need a different method other than <code>setWindowTitle</code> to change the title? Maybe from the centralWidget, or MenuBar, or some other element? And why did the title vanish in the first place?</p>
  
  <p>Ubuntu screenshot after first call of <code>setWindowTitle</code> -the title 'PicSel' is set on the application window title and on the top Ubuntu panel (or whatever this is called):</p>
  
  <p><img src="https://i.stack.imgur.com/cTMKi.png" alt="After first setWindowTitle"></p>
  
  <p>Ubuntu screenshot after second call of <code>setWindowTitle</code> - the title is not set on the application window itself, but on the very top panel:</p>
  
  <p><img src="https://i.stack.imgur.com/7cfKB.png" alt="After second setWindowTitle"></p>