Why some QT elements can be created as local and lives outside?

[tonnot]

This is a question that I have from time to time.
In example, the analog clock example shows how you can create a Qtimer object inside analog_clock constructor and it lives until you close the app.
The question, 'Why I have the impression that I see (somtimes) at Qt examples, objects that needs to be pointer based, created and deleted and some times I see objects created as 'locals' inside a method (and they works fine during the life of the prog..'
Or Maybe I see this always at constructor and in this case they have a singular treatment ?

I hope you understand this doubt.

Thanks.