When an editable ComboBox has the following model elements, the auto-completion will also match "banana", "bANANA" or any other variation. This causes a problem when you want to exactly match the strings.

ComboBox {
    editable: true
    model: ListModel {
        id: model
        ListElement { text: "Banana" }
        ListElement { text: "Apple" }
        ListElement { text: "Coconut" }
    }
}

In qquickcombox.cpp:459 in the acceptInput() function the find message uses Qt::MatchFixedString which is case insensitive per documentation.
The problem is that I do the handling completely in the custom ComboBox, but this acceptInput() function kicks in afterwards and sets the currentIndex again.

The suggestion is to introduce a property to set the Qt::MatchFlags for the acceptInput() case.