QwtPlotMarker example

Can someone post small example how can I add point (elipse) into QwtPlot?
qwt is great but examples are very poor documented.


sory for my english.

Code:

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QwtSymbol *sym=new QwtSymbol(QwtSymbol::Diamond,QBrush(Qt::red),QPen(Qt::red),QSize(5,5));
 QwtPlotMarker *mark=new QwtPlotMarker;
     mark->setSymbol(sym);
     mark->setValue(x,y);//here you have to set the coordinate axis i.e. where the axis are meeting.
     mark->attach(yourplot);

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