Need support for non-uniform positioner transitions

import QtQuick 2.0

Rectangle {
    width: 320
    height: 480

    property int deletedItemIndex: 0

    ListModel { id: theModel }
    Component.onCompleted: {
        for(var i = 0; i < 20; i++) {
            theModel.append( {} );
        }
    }

    Grid {
        anchors.centerIn: parent
        spacing: 10

        move: Transition {
            SequentialAnimation {
                ScriptAction { script: print("#### Grid's move-transition item index: " + index) }
                NumberAnimation { properties: "x, y"; duration: 300 + Math.max(index-deletedItemIndex, 0)*50 }
            }
        }

        Repeater {
            model: theModel
            delegate: Rectangle {
                width: 60; height: 60;
                color: "blue"

                MouseArea {
                    anchors.fill: parent
                    onClicked: {
                        deletedItemIndex = index;
                        theModel.remove(index);
                    }
                }
            }
        }
    }
}