Hi d_stranz,
I agree It might not be a good way, But as I told previously The evolution of app made us to take this kind of decision. And coming to UI, it don't has menubar, toolbar or status bar, So it looks cleaner and easy.
Qt Code: 
  4.                centralwidget
  5.                     all widgets under this screen
  7.                centralwidget
  8.                     all widgets under this screen
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I agree with the change, that All these windows should be Qwidgets, But it's like rewriting all my application again.
So do you think the constructors delay is caused by my approach only?

Thanks,
Nagendra