How to add a scrollbar to a Qcombobox

[semi]

i use python, and qt5, and qt designer. I want to add a scroll bar to the combo box. Any way to add a scrollbar using stylesheet? Other ways are also good. This is the stylesheet currently used in the combo box.
QComboBox {
combobox-popup: 0;
}
I use this because I want to show the drop down list in 10 order. There seems to be no more data below because there are no scrollbars at this time. If you know how, please help me. thanks!

[jsulm]

@semi Doesn't QComboBox add scroll bar automatically?

[Vineela]

@jsulm it has arrow at the top and end unless we click that arrow it scrolls but how to get scroll bar?????

[jsulm]

@Vineela I don't understand the problem: if there are too many items in the combo box to show them all at the same time then the combo box adds a scroll bar automatically.

[Kogotoro]

Qt 5.11.1 (MSVC 2015, 32 bit)

loading diffrent css
with
QComboBox { combobox-popup: 1 }
and
QComboBox { combobox-popup: 0 }
one after another
results crush when on form present editable combobox
for not editable it work fine