title: Make QLabel text selectable?
body: <p>I have a <code>QLabel</code> in my application that displays error messages to the user. I would like to make the text of the label selectable so users can copy and paste the error message if needed.</p>
  
  <p>However, when I use the mouse to click and drag over the text, nothing happens - the text is not selected.</p>
  
  <p>How can I make the text within a <code>QLabel</code> selectable by the mouse?</p>