Drag and Drop in QML TreeView with multiselection

[T-Man]

How can I implement drag & drop in a QtQuick TreeView without breaking the selection mechanism?

TreeView {
    id: treeview
    anchors.fill: parent
    model: myTestModel

    // broken due to MouseArea in itemDelegate !
    selectionMode: SelectionMode.ExtendedSelection
    selection: ItemSelectionModel {
        model: treeview.model
    }

    TableViewColumn {
        role: "name_role"
        title: "Name"
        width: 160
    }
    TableViewColumn {
        role: "type_role"
        title: "Type"
        width: 75
    }

    itemDelegate: Item {
        Rectangle {
            id: rect
            anchors.fill: parent
            color: styleData.selected ? "blue" : "transparent"
            Text {
                anchors.verticalCenter: parent.verticalCenter
                color: styleData.selected ? "white" : "black"
                text: styleData.value
            }
            MouseArea {
                anchors.fill: parent
                drag.target: symbolAvatar
                onPressed: {
                    var tmp = mapToItem(container, mouse.x, mouse.y);
                    symbolAvatar.x = tmp.x;
                    symbolAvatar.y = tmp.y;
                    symbolAvatar.dragging = true;
                    symbolAvatar.text = styleData.value;
                }
            }
        }
    }
}

The MouseArea inside the itemDelegate seems to be the common solution for drag and drop in TreeViews, but the selection does not work anymore if I add it.
So I can only make the selection OR the drag and drop work properly :-(

Any help would be appreciated!

Edit: Using the onPressAndHold event handler inside the TreeView would be a solution if I could access the mouse position there, but it doesn't seem to exist!

[T-Man]

By adding the line "property alias mouser: mouseArea" to the TreeView.qml of Qt, I can implement mouser.onPressed: {...} inside my TreeView code.
This way both the selection and drag&drop work, but I actually don't like the idea of modifying Qt code.

No one out there with an approach how to solve this a bit cleaner?