Crash in FastBlur / ShaderEffectSource

import QtQuick 2.5
import QtQuick.Window 2.2
import QtGraphicalEffects 1.0

Window {
    id: root
    visible: true
    FastBlur {
        id: _fastBlur
        anchors.fill: parent
        radius: 80
        source: ShaderEffectSource {
            id: _shaderEffectSource
            sourceRect: Qt.rect(root.x, root.y, root.width, root.height)
        }
    }
}