The doc states:
The Qt object contains all enums in the Qt namespace. For example, you can access the AlignLeft member of the Qt::AlignmentFlag enum with Qt.AlignLeft.
For a full list of enums, see the Qt Namespace documentation.
But trying to access Qt.AnchorLeft, for example, returns undefined. Qt::AnchorAttribute and Qt::AnchorPoint aren't present in the QML Qt global object.