How do I detect change of state for any widget in a page

[rawfool]

I have a QListWidget with 5 items and on click of each item, I'm showing corresponding widget pages which are in a stacked layout. I call whole of these as settings page which is similar to Microsoft Security Essentials settings tab. Pic of Microsoft Security Essentials - settings tab

Now on change of state in any of the widgets in the stacked layout, I need to enable "Save" and "Cancel" buttons. For example user changes check state or QComboxItem, or any of those widgets in each of the stacked layout. Do I need to connect all the widgets' state change signals to one slot ? Is there any better way to find change in any of the widgets state in the page at one go ? How do I find that ?
Thank you.