Access Arbortext Editor in an ActiveX control

I've received an answer from PTC support in the meantime which solves my problem. The point is that you have to instantiate the editor first with new ActiveXObject("Epic.Application"). Another important issue is to have proper, which means relaxed, ActiveX security settings in IE.

<script language="javascript" type="text/javascript" for="editor">

var application;
var appWindow;
var appDocument;

// This instantiates the Editor "application" object so it can be used later.
try
{
application = new ActiveXObject("Epic.Application");
}
catch (e)
{
alert(e.message);
}


var documentFlags = 0x0000;
var windowFlags = 0x949FF;
var aclWindowId;
var domDocument;
function OpenDoc(docUrl)
{
try
{
aclWindowId = editor.open(docUrl, documentFlags, windowFlags);

// Use the aclWindowId to gain access to the object model window and document objects.
appWindow = application.Acl.getWindow(aclWindowId);
appDocument = appWindow.activeView.document;

// Construct a message with some information from the window and document.
var message = "Window Width = " + appWindow.width;
message += ", Window Height = " + appWindow.height;
message += ", Window Left X = " + appWindow.screenX;
message += ", Window Left Y = " + appWindow.screenY;

message += "\n\nDocument Element = " + appDocument.documentElement.localName;
message += ", Document Element Child= " + appDocument.documentElement.firstChild.localName;


alert(message);
}
catch (e)
{
alert(e.message);
}
}

...

</script>