Need to resize the window to make QwtPlotSpectrogram shows correctly

[embeddedmz]

The problem is about a missing layout update - not replotting. And on my box the workaround solved it in the demo code ( note, that updateLayout needs to be alled after setAxisScale and before replot ). So maybe you are talking about a different situation/problem now ?

I called updateLayout just before replot, so after any eventual setAxisScale call. I even copied/pasted your code with the workaround in the demo and nothing changed !

My Qt version is 5.12.3 by the way and actually working under Ubuntu 18.04 (but will also run the program on Centos 7 later).

Like for the yRight axis's color bar issue (see the comment above), reassigning a new color map to the spectrogram object fixed my issue ! It's not pretty but it doesn't matter

m_spectrogram.setColorMap(new LinearColorMapRGB());

m_spectrogram.setColorMap(new LinearColorMapRGB());

To copy to clipboard, switch view to plain text mode 

Invalidating the cache worked perfectly ! Awesome, thank you !