title: Debugging mode for Qt GUI application
body: <p>I would like to add a debugging mode for Qt GUI application. In debugging mode, any GUI widget events would dump out debug information rather than doing the original functionality. For example, clicking <code>button A</code> would print out the checkbox options being selected, where <code>button A</code>'s original function is process something to the selected options.</p>
  
  <p>I was thinking to add a menu option "<code>debug mode</code>", or a secret keyboard shortcut to enable it. And in the callback functions associated with widget signals (<code>clicked</code>/ <code>textEdited</code>), use <code>if(isDebugMode)/else</code> to distinguish regular function mode code.</p>
  
  <p>Is this a good model to test GUI functionality? Is there any better way?</p>