import QtQuick import QtQuick.Controls Window { id: window Text {text: "Hello"} Popup { id: popup anchors.centerIn: parent dim: true property double dimmerOpacity: 0.5 Overlay.modeless: Rectangle { color: "blue" opacity: popup.dimmerOpacity Behavior on opacity { NumberAnimation { from: 0; to: popup.dimmerOpacity; duration: 250 } } } Overlay.modal: Rectangle { color: "blue" opacity: popup.dimmerOpacity Behavior on opacity { NumberAnimation { from: 0; to: popup.dimmerOpacity; duration: 250 } } } enter: Transition { NumberAnimation { property: "opacity"; from: 0; to: 1; duration: 250 } } exit: Transition { NumberAnimation { property: "opacity"; from: 1; to: 0; duration: 250 } } } }