Qt qml how to set applicationwindow as a child

in Qt qml how to set applicationwindow as a child of Rectangle, when applicationwindow moving out of Rectangle, the part does not display.

ApplicationWindow {
    id: border_window;
    objectName: "LayerItemWndView";

    Rectangle {
        id: rect;

         ApplicationWindow {
            id: layer_window;
            objectName: "layer_window";
        } 
    }
}