QML. Canvas is painted despite being invisible

import QtQuick 2.0

Rectangle {
    width: 800
    height: 600
    color: "seagreen"

    Canvas {
        id: canvas
        anchors.fill: parent
        visible: false
        onPaint: {
            console.log("visible:", visible)
            console.trace()
            var context = getContext("2d")
            context.save()
            context.fillStyle = "salmon"
            context.fillRect(0, 0, width, height)
            context.restore()
        }
    }

    MouseArea {
        anchors.fill: parent
        onPressed: canvas.requestPaint()
    }
}