I think that you should play with QClipboard class. Also there is a more complex way: look into qt sources, find how is clipboard handled in QTextEdit and change it in derived class.

QTextEdit class has createMimeDataFromSelection() method overriding which should do what I want. But I need an equivalent solution for QLineEdit (I need to use it in QDateEdit).

Oops, sorry, I meant that you can look int Qt sources how does QLineEdit handle it :)