QQuickWidget blank until resize

[ymhsieh]

I am trying to load and display the following QML using QQuickWidget. I think I hace setup everything correctly. However, the QQuickWidget shows a blank until I resize my main window. Any tip/hint so that I will be able to two the two rectangles on its initial display? (using Qt 5.9.1 on Win64 platform)

RowLayout {
anchors.fill: parent

Rectangle {
    color: 'blue'
    Layout.fillWidth: true
    Layout.fillHeight: true
}
Rectangle {
    color: 'green'
    Layout.fillWidth: true
    Layout.fillHeight: true
}

}