QwtScaleDraw - Hide Scale before QTime(0,0,0) ?

[Maximus2]

Hey,

I'm trying to hide the scale so that I don't get this invalid value before 00:00
See image:
https://www.dropbox.com/s/fblzeo5g8d...djust.png?dl=0

My custom plot is using this QwtScaleDraw:

class TimeScaleDraw: public QwtScaleDraw {
public:
    TimeScaleDraw( const QTime &base ):
        baseTime( base )
    {
    }
 
    virtual QwtText label( double v ) const {
        QTime upTime = baseTime.addSecs( static_cast<int>( v ) );
        return upTime.toString();
    }
 
private:
    QTime baseTime;
};

class TimeScaleDraw: public QwtScaleDraw {
public:
    TimeScaleDraw( const QTime &base ):
        baseTime( base )
    {
    }

    virtual QwtText label( double v ) const {
        QTime upTime = baseTime.addSecs( static_cast<int>( v ) );
        return upTime.toString();
    }

private:
    QTime baseTime;
};

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Any help/clues appreciated!
Thanks