Qt [undo]

[kjiu]

hi,

I must do in Qt a "undo" ( QKeySequence::Undo ) but I don't know do this.Help me

ex.

void MyWindow::Save ()
{
    QFile file (fileName);
    if (file.open (QFile::WriteOnly | QFile::Text))
    {
        QTextStream out (&file);
        out << textEdit -> toPlainText ();
        statusBar() -> showMessage ("message",2000);
    }
}

but this is for save .. a must do undo