I tried calling qwtPlot->replot() after start() was called, this didn't make any difference.

I have also tried passing the QwtPlot pointer to the class and running replot() with that pointer. This didn't make any difference.

When I added QwtPlot::replot() to the class it gave the following error:
"cannot call member function 'virtual void QwtPlot::replot()' without object"
I tried adding friend classes etc.

I don't seem to have the same problem with my custom QwtPlotPicker.

Please excuse my stupidity in advance