Close an HTA when the user presses the 'Esc' key

I'm trying to capture key presses so that I can close my HTA when the user presses the Esc key.

I have confirmed that the onKeyUp event works (I also capture the length of an input), and also that the example below is not working (by adding a MsgBox which is not fired).

What am I missing here?

Sub window_onKeyUp()

    If window.event.keyCode = 27 Then
        Call CloseHTA()
    End If

End Sub

Solution

This works for me.

<script language="VBScript">
    Sub TestKey()
        intKeyCode = Window.Event.Keycode
        If intKeyCode = 27 Then Window.Close
    End Sub
</script>

<body onkeyup="TestKey">
</body>

Edit:

Alternatively, you can use Document_OnKeyUp() if you want to include your code after the <body> tag.

<body>
</body>

<script language="VBScript">
    Sub Document_OnKeyUp()
        intKeyCode = Window.Event.Keycode
        If intKeyCode = 27 Then Window.Close
    End Sub
</script>