A couple of questions about the Qt GUI?

Question

Qt

How can I make it so that when I right-click on the Item-a line in the ListWidget, I can select an action i.e. do something like this:

And how do I set that when closing the window (pressing the cross in the window) I performed some function before it closes, for example, saving data to a file

Answer 1

I performed some function before it closes, for example, saving data to a file

doc.crossplatform.ru/qt/4.6.x/eventsandfilters.html

Answer 2

For the first case - it's called "context menu" - google how it's done in Qt.
For the second case, as Alexander Taratin already answered , there are events.

Answer 3

How can I make it so that when I right-click on the Item-a line in the ListWidget, I can select an action i.e. do something like this:

This can be done with a context menu that is invoked and the concept of signals/slots.
By overloading the closeEvent() method .
I suggest you look at this small example and understand it:
Example source code: dropmefiles.com/wRUFj
Good luck!