1. Set a device profile to use Fusion style.
2. Refer the attached project.
The style of Push Button is Fusion, but the style of Tab Widget is not Fusion
when editing the form and previewing the form.

The style of the application when I execute it by setting a style as follows,
app.setStyle(QStyleFactory::create("Fusion"));
No problem.

The style of Tab Widget should be the style of a device profile for editing
and preview.