I'm going through the QA testing now and found a small bug:
(it won't prevent a thumbs up vote, since it's a small bug)

When "Sort A-Z" is enabled, uppercase comes before lowercase, while it shouldn't make a diffference. Maybe "Qt::CaseInsensitive" will solve it
Also, I had 1, 2, 10 and 20 in the list.
The were shown in this order:
1
10
2
20
Not a big issue, but it might be better to make it count as normal. That seems quite hard to accomplish to me