qwt plots & inheritance

[fatecasino]

well, I am doing something definitely wrong, but I can't find it..

I followed the steps of "bode" example and created a class called my2dplot
In the constructor of the class I implemented everything, like axis titles, how to get data, attach curves, etc.

class my2dPlot : public QwtPlot
{
    Q_OBJECT
 
public:
    my2dPlot(QWidget *parent = 0);
    //    int value() const;
 public Q_SLOTS:
        void setDamp(double damping);
public slots:
    //general purpose functions
    void gridOn(); //sets the grid on-off
    double** getCurveData();//returns the data from file
 
    //main spectroscopy curve functions
    void attachData2Curve(double**);//attach data to main curve
    void attachCurve2Plot();//attach main curve to plot widget
    void plotMainCurve(const QString &fileName  );//function to call when you want to plot the main curve
    //it includes the call of the three previous functions
    //getCurveData, attachData2Curve, attachCurve2Plot
    int getDataSize(); //returns the size of the data
    void setDataSize(int);//sets the data size
 
    //Continuum Curve functions
    void attachData2Continuum(double**);//attach data to Continuum curve
    void attachContinuum2Plot();//attach Continuum curve to plot widget
    void plotContinuumCurve(QString &fileName);//function to call when you want to plot the Continuum curve
 
    //set the data file name to read
    void setDataFile (QString);
    //get the data file name to read
    QString getDataFile ();
private slots:
 
 
signals:
 
private:
    QwtPlot *myPlot;
    QwtPlotGrid *grid;
 
    QwtPlotCurve *mainCurve;
    QwtPlotMarker *mainCurveMarker;
 
    QwtPlotCurve *continuumCurve;
    QwtPlotMarker *continuumCurveMarker;
    QString dataFile;
    int dataSize;
 
};

class my2dPlot : public QwtPlot
{
    Q_OBJECT

public:
    my2dPlot(QWidget *parent = 0);
    //    int value() const;
 public Q_SLOTS:
        void setDamp(double damping);
public slots:
    //general purpose functions
    void gridOn(); //sets the grid on-off
    double** getCurveData();//returns the data from file

    //main spectroscopy curve functions
    void attachData2Curve(double**);//attach data to main curve
    void attachCurve2Plot();//attach main curve to plot widget
    void plotMainCurve(const QString &fileName  );//function to call when you want to plot the main curve
    //it includes the call of the three previous functions
    //getCurveData, attachData2Curve, attachCurve2Plot
    int getDataSize(); //returns the size of the data
    void setDataSize(int);//sets the data size

    //Continuum Curve functions
    void attachData2Continuum(double**);//attach data to Continuum curve
    void attachContinuum2Plot();//attach Continuum curve to plot widget
    void plotContinuumCurve(QString &fileName);//function to call when you want to plot the Continuum curve

    //set the data file name to read
    void setDataFile (QString);
    //get the data file name to read
    QString getDataFile ();
private slots:


signals:

private:
    QwtPlot *myPlot;
    QwtPlotGrid *grid;

    QwtPlotCurve *mainCurve;
    QwtPlotMarker *mainCurveMarker;

    QwtPlotCurve *continuumCurve;
    QwtPlotMarker *continuumCurveMarker;
    QString dataFile;
    int dataSize;

};

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Then I created a central widget including a member of my2dplot

class QwtPlotZoomer;
class QwtPlotPicker;
class QwtPlotPanner;
class my2dPlot;
class QPolygon;
 
 
class MyWidget : public QWidget
{
public:
    MyWidget(QWidget *parent = 0);
    my2dPlot *mainPlot;
 
protected:
 
private slots:
 
private Q_SLOTS:
    void moved(const QPoint &);
    void selected(const QPolygon &);
 
#ifndef QT_NO_PRINTER
    void print();
#endif
    void exportDocument();
    void enableZoomMode(bool);
 
signals:
 
 
private:
    //my2dPlot *mainPlot;
    QPushButton *quitButton;
 
    void showInfo(QString text = QString::null);
    QwtPlotZoomer *d_zoomer[2];
    QwtPlotPicker *d_picker;
    QwtPlotPanner *d_panner;
};

class QwtPlotZoomer;
class QwtPlotPicker;
class QwtPlotPanner;
class my2dPlot;
class QPolygon;


class MyWidget : public QWidget
{
public:
    MyWidget(QWidget *parent = 0);
    my2dPlot *mainPlot;

protected:

private slots:

private Q_SLOTS:
    void moved(const QPoint &);
    void selected(const QPolygon &);

#ifndef QT_NO_PRINTER
    void print();
#endif
    void exportDocument();
    void enableZoomMode(bool);

signals:


private:
    //my2dPlot *mainPlot;
    QPushButton *quitButton;

    void showInfo(QString text = QString::null);
    QwtPlotZoomer *d_zoomer[2];
    QwtPlotPicker *d_picker;
    QwtPlotPanner *d_panner;
};

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and then I set this widget as the mainWidget in the mainwindow.h

The problem is that in the main window a plot area appears (with no background color-grey) and it does not show ANYTHING of what is described in the constructor of my2dclass. How is this possible? I mean, how is it possible that the widget creates a qwt plot (actually a my2dplot plot) and it does not take into consideration the rest of the my2dclass constructor?

It must be something obvious, but I cannot really see it!