Custom QwtPlot class

[Uwe]

Without knowing about the declaration/assignment of the plotpage variable nobody can tell you if your code is correct. IMO the only reasonable situation where your cast makes sense is something like this:

QWidget *plotpage = plot1; // something derived from QwtPlot
// ...
QwtPlot *plot2 = dynamic_cast<QwtPlot *>(plotpage);

QWidget *plotpage = plot1; // something derived from QwtPlot
// ...
QwtPlot *plot2 = dynamic_cast<QwtPlot *>(plotpage);

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As long as you don't have rtti disabled don't use static_casts for situations like this.

Uwe