CombBox: Don't change on scroll uless we have focus

[ogoffart]

This is what native Windows combobox does.
Otherwise this causes problem when combobox are in scrollable

Fixes #5929

[NigelBreslaw]

At least on MacOS there are no situations you can scroll the values of a combo box. Focused or not. However with either keyboard or mouse once the combo box is opened and showing the list of values those can be scrolled. I just tested on Windows 11 and it seems the same? You have to open the combo box list of items first via a click or keyboard activation. At least in the system settings pages I tried.

[ogoffart]

I just tested on Windows 11 and it seems the same? You have to open the combo box list of items first via a click or keyboard activation. At least in the system settings pages I tried.

I Just tested in the system settings and when the ComboBox has the keyboard focus, and you scroll over it with the mouse wheel, it does change its values.

[ogoffart]

According to https://doc.qt.io/qt-6/qstyle.html#:~:text=SH_ComboBox_AllowWheelScrolling , Qt also disable the wheel on the combobox on mac, so i've disabled it for the cupertino style