target.cshtml

@using TXTextControl.Web
@using TXTextControl.Web.MVC

@Html.TXTextControl().TextControl(settings =>
{
    settings.Dock = DockStyle.Window;
}).Render()

<script>
    window.onload = function () {

        function receiveMessage(e) {
          
            if (e.origin !== "http://localhost:3053")
                return;

            var message = JSON.parse(e.data);

            if (message.txtextcontrol == null)
                return;

            switch (message.txtextcontrol.method) {
                case "loadDocument": {
                    var encoded = btoa(message.txtextcontrol.parameter); 
                    TXTextControl.loadSelection(TXTextControl.StreamType.HTMLFormat, encoded);
                }
             }
        }

        window.addEventListener('message', receiveMessage);
    }
</script>