Detecting when the delete key was pressed on a listwidget item

[jpn]

Is there any way to add a custom slot to an existing class so I don't need to create a whole new class?

Basically any QObject derivated class having access to the list widget goes. So if you already have subclassed for example QMainWindow and the list widget is inside it, you could add the slot into the main window and do the deletion from there. However, don't be afraid of subclassing. I do personally like subclassing a lot and tend to put myself the functionality where it belongs and makes the most sense..