If you create a simple TabView even with just one Tab in it and you enable the default Mac behavior where tab focus only affects list of Text Fields, it will enter a live loop the moment you press a tab button.

Example:

 
ApplicationWindow {
    title: "Component Gallery"

    width: 580
    height: 400
    TabView {
        id:frame
       anchors.fill: parent

        Tab {
            id: controlPage
            title: "Control"
        }
        Tab {
            title: "Itemviews"
        }
    }
}

It goes to an infinite loop in QQuickItemPrivate::nextPrevItemInTabFocusChain().