[alien1993]

You could use Quick Controls 2, they can be styled easily. http://doc.qt.io/qt-5/qtquickcontrols2-index.html

[jcelerier]

There is a Quick Controls 2 style that uses the Qt Widget looks : https://github.com/KDE/qqc2-desktop-style

[CarVac]

You can style the original Controls too, but I've never tried for a native look in my photo editor.