Strange behavior: double click/mouse dragging will trigger key event “CTRL-C”

[koderchen]

Qt seems to behavior strangely: when mouse double click or dragging on a widget, it will trigger the Ctrl-C key event. Here is my code:

class CWidget: public QWidget
{
    Q_OBJECT
 
public:
    CWidget()
    {
 
    };
    virtual ~CWidget()
    {
    }
 
protected:
    void keyPressEvent ( QKeyEvent * event ) 
    {
        if (event->key() == Qt::Key_C && (event->modifiers() & Qt::ControlModifier))
        {
            qDebug() << "strange copy: Ctrl-C";
        }
        QWidget::keyPressEvent(event);
    }
}; //

class CWidget: public QWidget
{
    Q_OBJECT

public:
    CWidget()
    {

    };
    virtual ~CWidget()
    {
    }

protected:
    void keyPressEvent ( QKeyEvent * event ) 
    {
        if (event->key() == Qt::Key_C && (event->modifiers() & Qt::ControlModifier))
        {
            qDebug() << "strange copy: Ctrl-C";
        }
        QWidget::keyPressEvent(event);
    }
}; //

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After the widget is shown, you can perform mouse double click and dragging around on it, and the debug message "strange copy:Ctrl-C" is printed. I have been searching over the internet for two days about this, and found nothing.

Did I code it wrong or it is a bug of Qt?

The code is tested under (vs2008 + Qt Addin + Qt 4.7.3) and (qcreator + Qt 4.7.3 ), xp sp2

Here is the project can be compiled using vs2008 + Qt Addin + Qt 4.7.3:
CWidget.zip

[wysota]

Please provide a minimal compilable example reproducing the problem.

[Spitfire]

Hmmm I can't see any strange behaviour (w7 64bit, qt creator, qt4.6.3/qt4.7.4).