In the case I add to MainWindow style sheet some think like this:

QTabBar::scroller{

width: 30px;

}

Then I got only right-ward scroll button (left button dissapear). It cause this qss feature is useless. Due this bug I am forced to use default thin buttons in the touch screen device!!! Now our users are forced to use special "touch stick" instead just fingers. But in the future I want to set globally widgets scale (I heard it is possible in Qt) to avoid that...

I attach screenshots and minimal working example to show this bug.