Creating child page popup using a response object disrupts formatting of parent page

Question

I've got a web page from which I'm spawning a pop-up with a response object to create/download a vcard. It functions as expected, but the font size on my parent page becomes huge, and only reverts back to its original when I refresh the page. How do I fix that?

My call to the vcard popup:

 Response.Write(@"<script language = 'Javascript'>var" +
                        @" win=window.open('vCard.aspx',null,'width=50,height=50," +
                        @"top=100,left=100','true');</script>");

Vcard creation:

 public static void VCard(HttpResponse response)
    {
        response.Clear();
        response.Charset = "";
        response.ContentType = "text/x-vCard";
        System.IO.StringWriter stringWrite = new System.IO.StringWriter();
        System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);

            {
                response.AddHeader("content-disposition", "attachment; filename=" + usr.SamAccountName);

                stringWrite.WriteLine("BEGIN:VCARD");
                stringWrite.WriteLine("VERSION:2.1");
                //Name
                stringWrite.WriteLine("N:" + usr.LastName + ";" + usr.FirstName
                    );
               //removed other vcard lines....

                //vCard End
                stringWrite.WriteLine("END:VCARD");
                response.Write(stringWrite.ToString());
                response.End();
            }
    }

Answer 1

Using Response.Write before the Response is fully formed and sent back to the browser will cause the string to be written to the front of the stream.

There is actually a specific method to service this need, ClientScriptManager.RegisterClientScriptBlock :

ClientScript.RegisterClientScriptBlock(this.GetType(), "scriptKeyNameCanBeAnythingYouWant", "var
                    @" win=window.open('vCard.aspx',null,'width=50,height=50," +
                    @"top=100,left=100','true');", true);

Reference for ClientScriptManager.RegisterClientScriptBlock : http://msdn.microsoft.com/en-us/library/bahh2fef.aspx