Mark Document Readonly (and make it stick)

I found an unpleasnt hack by using beforeDocumentChange and setting the docs readonly there.  This throws a ReadOnlyModificationException in the log. Setting the virtualfile to readonly changes the on disk perms.  I coud rewind the change, but that is equally stupid.  Surely there is some sane way of ding this?

The current solution is to undo the current change and the mark the document readonly (which spams the console).

        final Document document = event.getDocument();
        final String text = document.getText();

        context.setTimeout(0, new Runnable() {
            @Override
            public void run() {
                ThreadSafe.write(context, new Runnable() {
                    @Override
                    public void run() {
                        isListening.set(false);
                        document.setReadOnly(false);
                        document.setText(text);
                        document.setReadOnly(true);
                        isListening.set(true);
                    }
                });
            }
        });
        document.setReadOnly(true);