CompassContext.cs

public static MvcHtmlString CompassUrl(this HtmlHelper helper, string compassUrl)
{
  //...
    var anchorBuilder = new TagBuilder("a");
    anchorBuilder.Attributes.Add("target", IsCompassContext(helper) ? "_parent" : "_blank");
    anchorBuilder.Attributes.Add("href", compassUrl);
  //...
}

private static bool IsCompassContext(HtmlHelper helper)
{
    var context = (helper.ViewContext.HttpContext.ApplicationInstance).Request.Params["context"];
    // if in Compass, make the hyperlink redirect the parent page instead of opening a new blank page
    return context != null && context.ToLower() == "compass";
}