This is quite expected since QWidget
has no such a member. That is a QFrame
member method.
void QFrame::setFrameStyle(int style)
Note, the canvas getter will return the following type, and not necessarily a QFrame
:
QWidget * QwtPlot::canvas();
const QWidget * QwtPlot::canvas() const;
It should be checked with dynamic/qobject_cast if the returned value is actually a QFrame
.