KeyEventViewer.qml

import QtQuick 2.1
import QtQuick.Controls 1.0
import QtQuick.Window 2.0

ApplicationWindow {
    title: qsTr("Key Event Viewer")
    width: 640
    height: 480

    Text {
        id: outputText
        anchors.fill: parent
        font.pointSize: 64

        horizontalAlignment: Text.AlignHCenter
        verticalAlignment: Text.AlignVCenter

        text: "waiting..."
    }

    Item {
        focus: true

        Keys.onPressed: {
            outputText.text = event.key + " pressed";
        }

        Keys.onReleased: {
            outputText.text = event.key + " released";
        }
    }

}