EPiServer - Detecting Block editing

Index.cshtml

@using EPiServer.Core
@using EPiServer.Editor
@using EPiServer.Web.Mvc.Html

@model MyWebsite.Models.BlockTypes.EmergencyNotificationBlock

<div class="card-static full">
    <div class="emergency-notification">
        <div class="icon @Model.AlertType.ToString().ToLower()"></div>
        <div class="wrapper">
            <h2>@Html.PropertyFor(m => m.Title)</h2>
            <p>@Html.PropertyFor(m => m.Copy)</p>
            <a href="@Model.LinkPage.Uri" target="_blank" class="cta">More Details</a>
        </div>
    </div>
</div>

@if (ViewBag.IsInBlockPreview == true)
{
    <div class="page-editing">
        <strong>Alert type: </strong>
        @Html.PropertyFor(m => m.AlertType)
        <br />
        <strong>Link page:</strong>
        @Html.PropertyFor(m => m.LinkPage)
    </div>
}

PreviewController.cs

using EPiServer.Web.Mvc;

namespace MyWebsite.Controllers
{
    /// <summary>
    /// Preview controller base.
    /// </summary>
    public abstract class PreviewController : ActionControllerBase
    {
        public PreviewController()
        {
            // Set a flag for block views to use to detect if the block is being edited vs being rendered in a content area when the whole page is being edited
            ViewBag.IsInBlockPreview = true;
        }
    }
}

PreviewMyComponentController.cs

using EPiServer;
using EPiServer.Core;
using EPiServer.Framework.DataAnnotations;
using EPiServer.Framework.Web;
using EPiServer.Web;
using EPiServer.Web.Mvc;
using MyWebsite.Models.BlockTypes;
using MyWebsite.Models.PageTypes;
using MyWebsite.Models.ViewModels;
using System.Web.Mvc;

namespace MyWebsite.Controllers
{
    [ContentOutputCache(Disable = true,  NoStore = true, VaryByParam = "*", Duration = 0)]
    [TemplateDescriptor(
        Inherited = true,
        TemplateTypeCategory = TemplateTypeCategories.MvcController,
        Tags = new[] { RenderingTags.Preview, RenderingTags.Edit },
        AvailableWithoutTag = false)]
    public class PreviewDashboardCardController : PreviewController, IRenderTemplate<DashboardCardBlockBase>
    {
        public ActionResult Index(IContent currentContent)
        {
            var model = new DashboardPreviewModel(new MyWebsiteBasePage(), currentContent);
            return View(model);
        }
    }
}