Positioner's (row, column, grid, flow) positioning routines (prePositioning, doPositioning) are executed multiple times during construction

import Qt 4.7
Row {
    spacing: 2
    Rectangle { color: "red"; width: 50; height: 50; anchors.left: greenRect.right }
    Rectangle { id: greenRect; color: "green"; width: 20; height: 50 }
    Rectangle { color: "blue"; width: 50; height: 20 }
}