Uwe,

I made a quick example here https://github.com/embeddedmz/qwt_sp..._issue_example

To reproduce the issue, show the "Plot" tab, then go back to the "Button" tab and click on its content (it's a button !), then go back to the "Plot" tab. You will see, for example, that the labels of the right y axis are overflowing.

If you press on the button without passing by the "Plot" tab, there will be no problem !

Maybe the problem is I'm setting an axis scale before rendering it ?

d_plot->d_spectrogram->setData( new SpectrogramData() );
d_plot->setAxisScale( QwtPlot::yRight, 100000, 900000 ); // <==== ????
d_plot->replot();
You can also check that without fixing a size policy, the plots are small !

Regards.