Qwt Plot Grid and Plot Background problem when updating qwt 5.2.3 to 6.1.6

[Uwe]

Your draw methods are not overriding - they have a QRect while QwtPlotItem::draw has a QRectF in the signature.
Using the C++11 override keyword would have told you.

HTH,
Uwe

[olredi]

Thanks a lot. That solves my problem.

Using the C++11 override keyword would have told you.

Did not see anything regarding override.

Thanks,
olredi

[d_stranz]

Did not see anything regarding override.

"override" is a new keyword starting in C++11. You place it at the end of the declaration of a virtual class method that you are overriding. If you make a mistake in the declaration (QRect instead of QRectF for example) the compiler will issue an error because the signature is wrong.

void draw(QPainter *painter, const QwtScaleMap &, const QwtScaleMap &, const QRect &rect) const override;

void draw(QPainter *painter, const QwtScaleMap &, const QwtScaleMap &, const QRect &rect) const override;

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would cause a compile error with Qwt 6.