Just like this pic shows.Although I set the button rgba(x,x,x,40) which is transparent in my code,the button named “Adjust” is not transparent in the blue QVTKWidget .
I think this is a qt thing. As far as I understand the qvtkwidget is rendered separately from the rest of the controls.
If you to ask this question in the qt forum instead of here then you will be more likely to get a useful response.
Thankfor your advice.