How to add animation after PopupWindow.show()/before PopupWindow.close()?

[PleaseDont]

I tried to use transition, but not work.

export component AppWindow inherits Window {
    width: 400px;
    height: 300px;

    Button {
        text: "Open Dialog";
        clicked => {
            dialog.show();
        }
    }

    dialog := PopupWindow {
        width: root.width;
        height: root.height;

        states [
            show when self.visible: {
                mask.background: #00000066;
                in {
                    animate mask.background { duration: 300ms; }
                }
                out {
                    animate mask.background { duration: 300ms; }
                }
            }
        ]

        mask := Rectangle {
            background: transparent;
        }
    }
}

And, how to resize the PopupWindow when resizing the Window?

[ultimaweapon]

And, how to resize the PopupWindow when resizing the Window?

I also having the same problem. Was tried both placing the PopupWindow inside a layout and using change callback on the width and height on the window, none of them are working.