doubt in padnavigator example

[wagmare]

hi friends,
i am following the padnavigator example ... /qt4.4.3/example/graphicsview/padnavigator

in this example
in roundrectitem.h
the code is

class RoundRectItem : public QObject, public QGraphicsRectItem
{
    Q_OBJECT
public:
    RoundRectItem(const QRectF &rect, const QBrush &brush, QWidget *embeddedWidget = 0);

class RoundRectItem : public QObject, public QGraphicsRectItem
{
    Q_OBJECT
public:
    RoundRectItem(const QRectF &rect, const QBrush &brush, QWidget *embeddedWidget = 0);

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why we want to inherit QObject and also the Q_OBJECT macro .. either one is enough ...?

[wysota]

Because we want signals and slots to be available for the item - we need to inherit QObject for that and without Q_OBJECT macro one can't add new signals or slots to the class.