diff --git a/ext/src/shim/cast/index.ts b/ext/src/shim/cast/index.ts
index 25b3cb7..3f533f5 100755
--- a/ext/src/shim/cast/index.ts
+++ b/ext/src/shim/cast/index.ts
@@ -33,7 +33,7 @@ import { onMessage, sendMessageResponse } from "../messageBridge";
 
 type ReceiverActionListener = (
         receiver: Receiver
-      , receiverAction: typeof ReceiverAction) => void;
+      , receiverAction: string) => void;
 
 type RequestSessionSuccessCallback = (
         session: Session
diff --git a/ext/src/shim/framework/GoogleCastLauncher.ts b/ext/src/shim/framework/GoogleCastLauncher.ts
new file mode 100644
index 0000000..23a845d
--- /dev/null
+++ b/ext/src/shim/framework/GoogleCastLauncher.ts
@@ -0,0 +1,78 @@
+"use strict";
+
+/**
+ * Custom element for a cast button used by sites that injects
+ * a cast icon and manages visibility state and event handling.
+ */
+export default class GoogleCastLauncher extends HTMLElement {
+    constructor () {
+        super();
+
+        this.style.display = "none";
+
+        const style = document.createElement("style");
+        style.textContent = `
+            .cast_caf_state_c {
+                fill: var(--connected-color, #4285f4);
+            }
+            .cast_caf_state_d {
+                fill: var(--disconnected-color, #7d7d7d);
+            }
+            .cast_caf_state_h {
+                opacity: 0;
+            }
+        `;
+
+        // tslint:disable:max-line-length
+
+        const SVG_NAMESPACE = "http://www.w3.org/2000/svg";
+
+        const icon = document.createElementNS(SVG_NAMESPACE, "svg");
+        const iconArch0 = document.createElementNS(SVG_NAMESPACE, "path");
+        const iconArch1 = document.createElementNS(SVG_NAMESPACE, "path");
+        const iconArch2 = document.createElementNS(SVG_NAMESPACE, "path");
+        const iconBox = document.createElementNS(SVG_NAMESPACE, "path");
+        const iconBoxFill = document.createElementNS(SVG_NAMESPACE, "path");
+
+        // Set SVG attributes
+        icon.setAttribute("x", "0");
+        icon.setAttribute("y", "0");
+        icon.setAttribute("width", "100%");
+        icon.setAttribute("height", "100%");
+        icon.setAttribute("viewBox", "0 0 24 24");
+
+        iconArch0.classList.add("cast_caf_state_d");
+        iconArch0.setAttribute("id", "cast_caf_icon_arch0");
+        iconArch0.setAttribute("d", "M1 18v3h3c0-1.7-1.34-3-3-3z");
+
+        iconArch1.classList.add("cast_caf_state_d");
+        iconArch1.setAttribute("id", "cast_caf_icon_arch1");
+        iconArch1.setAttribute("d", "M1 14v2c2.76 0 5 2.2 5 5h2c0-3.87-3.13-7-7-7z");
+
+        iconArch2.classList.add("cast_caf_state_d");
+        iconArch2.setAttribute("id", "cast_caf_icon_arch2");
+        iconArch2.setAttribute("d", "M1 10v2c4.97 0 9 4 9 9h2c0-6.08-4.93-11-11-11z");
+
+        iconBox.classList.add("cast_caf_state_d");
+        iconBox.setAttribute("id", "cast_caf_icon_box");
+        iconBox.setAttribute("d", "M21 3H3c-1.1 0-2 .9-2 2v3h2V5h18v14h-7v2h7c1.1 0 2-.9 2-2V5c0-1.1-.9-2-2-2z");
+
+        iconBoxFill.classList.add("cast_caf_state_h");
+        iconBoxFill.setAttribute("id", "cast_caf_icon_boxfill");
+        iconBoxFill.setAttribute("d", "M5 7v1.63C8 8.6 13.37 14 13.37 17H19V7z");
+
+        // Add icon paths to SVG
+        icon.append(iconArch0, iconArch1, iconArch2, iconBox, iconBoxFill);
+
+        // tslint:enable:max-line-length
+
+
+        const shadow = this.attachShadow({ mode: "open" });
+        shadow.append(icon, style);
+
+
+        this.addEventListener("click", ev => {
+            console.info("<google-cast-launcher> onClick");
+        });
+    }
+}
diff --git a/ext/src/shim/framework/classes/CastContext.ts b/ext/src/shim/framework/classes/CastContext.ts
index 814f40d..674a28a 100644
--- a/ext/src/shim/framework/classes/CastContext.ts
+++ b/ext/src/shim/framework/classes/CastContext.ts
@@ -1,20 +1,14 @@
 "use strict";
 
+import * as cast from "../../cast";
+
 import CastOptions from "./CastOptions";
 import CastSession from "./CastSession";
 import CastStateEventData from "./CastStateEventData";
 import SessionStateEventData from "./SessionStateEventData";
 
 
-type EventHandler = (eventData:
-        CastStateEventData
-      | SessionStateEventData) => void;
-
-export default class CastContext {
-    public addEventListener (type: string, handler: EventHandler): void {
-        console.info("STUB :: CastContext#addEventListener");
-    }
-
+export default class CastContext extends EventTarget {
     public endCurrentSession (stopCasting: boolean): void {
         console.info("STUB :: CastContext#endCurrentSession");
     }
@@ -34,10 +28,6 @@ export default class CastContext {
         console.info("STUB :: CastContext#getSessionState");
     }
 
-    public removeEventListener (type: string, handler: EventHandler): void {
-        console.info("STUB :: CastContext#removeEventListener");
-    }
-
     // @ts-ignore
     public requestSession (): Promise<string> {
         console.info("STUB :: CastContext#requestSession");
@@ -47,3 +37,5 @@ export default class CastContext {
         console.info("STUB :: CastContext#setOptions");
     }
 }
+
+export const instance = new CastContext();
diff --git a/ext/src/shim/framework/classes/CastSession.ts b/ext/src/shim/framework/classes/CastSession.ts
index 7b6ec0b..2ff35ad 100644
--- a/ext/src/shim/framework/classes/CastSession.ts
+++ b/ext/src/shim/framework/classes/CastSession.ts
@@ -10,28 +10,15 @@ import MediaSessionEventData from "./MediaSessionEventData";
 import VolumeEventData from "./VolumeEventData";
 
 
-type EventHandler = (eventData:
-        ApplicationStatusEventData
-      | ApplicationMetadataEventData
-      | ActiveInputStateEventData
-      | MediaSessionEventData
-      | VolumeEventData) => void;
-
 type MessageListener = (namespace: string, message: string) => void;
 
 
-export default class CastSession {
+export default class CastSession extends EventTarget {
     constructor (sessionObj: cast.Session, state: string) {
+        super();
         console.info("STUB :: CastSession#constructor");
     }
 
-    public addEventListener (
-            type: string
-          , handler: EventHandler): void {
-
-        console.info("STUB :: CastSession#addEventListener");
-    }
-
     public addMessageListener (
             namespace: string
           , listener: MessageListener): void {
@@ -98,13 +85,6 @@ export default class CastSession {
         console.info("STUB :: CastSession#loadMedia");
     }
 
-    public removeEventListener (
-            type: string
-          , handler: EventHandler): void {
-
-        console.info("STUB :: CastSession#removeEventListener");
-    }
-
     public removeMessageListener (
             namespace: string
           , listener: MessageListener): void {
diff --git a/ext/src/shim/framework/classes/RemotePlayerController.ts b/ext/src/shim/framework/classes/RemotePlayerController.ts
index ee8311a..b8314de 100644
--- a/ext/src/shim/framework/classes/RemotePlayerController.ts
+++ b/ext/src/shim/framework/classes/RemotePlayerController.ts
@@ -4,17 +4,12 @@ import RemotePlayer from "./RemotePlayer";
 import RemotePlayerChangedEvent from "./RemotePlayerChangedEvent";
 
 
-type EventHandler = (event: RemotePlayerChangedEvent) => void;
-
-export default class RemotePlayerController {
+export default class RemotePlayerController extends EventTarget {
     constructor (player: RemotePlayer) {
+        super();
         console.info("STUB :: RemotePlayerController#constructor");
     }
 
-    public addEventListener (type: string, handler: EventHandler): void {
-        console.info("STUB :: RemotePlayerContoller#addEventListener");
-    }
-
     public getFormattedTime (timeInSec: number): string {
         const hours = Math.floor(timeInSec / 3600) % 24;
         const minutes = Math.floor(timeInSec / 60) % 60;
@@ -41,10 +36,6 @@ export default class RemotePlayerController {
         console.info("STUB :: RemotePlayerController#playOrPause");
     }
 
-    public removeEventListener (type: string, handler: EventHandler): void {
-        console.info("STUB :: RemotePlayerController#removeEventListener");
-    }
-
     public seek (): void {
         console.info("STUB :: RemotePlayerController#seek");
     }
diff --git a/ext/src/shim/framework/index.ts b/ext/src/shim/framework/index.ts
index 442ee9d..faaf38c 100644
--- a/ext/src/shim/framework/index.ts
+++ b/ext/src/shim/framework/index.ts
@@ -6,7 +6,7 @@ import ActiveInputStateEventData from "./classes/ActiveInputStateEventData";
 import ApplicationMetadata from "./classes/ApplicationMetadata";
 import ApplicationMetadataEventData from "./classes/ApplicationMetadataEventData";
 import ApplicationStatusEventData from "./classes/ApplicationStatusEventData";
-import CastContext from "./classes/CastContext";
+import CastContext, { instance } from "./classes/CastContext";
 import CastOptions from "./classes/CastOptions";
 import CastSession from "./classes/CastSession";
 import CastStateEventData from "./classes/CastStateEventData";
@@ -26,12 +26,11 @@ import { ActiveInputState
        , SessionEventType
        , SessionState } from "./enums";
 
+import GoogleCastLauncher from "./GoogleCastLauncher";
 
 import { onMessage } from "../messageBridge";
 
 
-let castContext: CastContext = null;
-
 export default {
     // Enums
     ActiveInputState, CastContextEventType, CastState, LoggerLevel
@@ -52,12 +51,7 @@ export default {
         ...CastContext
 
       , getInstance () {
-            if (castContext) {
-                return castContext;
-            }
-
-            castContext = new CastContext();
-            return castContext;
+            return instance;
         }
     }
 
@@ -67,3 +61,19 @@ export default {
         console.info("STUB :: cast.framework.setLoggerLevel");
     }
 };
+
+
+/**
+ * The Framework API defines a <google-cast-launcher> element
+ * and a <button is="google-cast-button"> element extension,
+ * both of which produce the same result.
+ *
+ * Chrome allowed custom elements to extend <button> elements
+ * via Element#createShadowRoot, but the standard
+ * Element#attachShadow method supported in Firefox specifies a
+ * limited whitelist of elements that are extendable.
+ *
+ * It's not officially advertised in the cast docs, so it
+ * shouldn't be much of a compatibility issue to ignore it.
+ */
+customElements.define("google-cast-launcher", GoogleCastLauncher);
diff --git a/ext/src/shim/index.ts b/ext/src/shim/index.ts
index fe946b5..7fc74ef 100755
--- a/ext/src/shim/index.ts
+++ b/ext/src/shim/index.ts
@@ -5,13 +5,13 @@ import * as cast from "./cast";
 import { onMessage } from "./messageBridge";
 
 
-const global = (window as any);
+const _window = (window as any);
 
-if (!global.chrome) {
-    global.chrome = {};
+if (!_window.chrome) {
+    _window.chrome = {};
 }
 
-global.chrome.cast = cast;
+_window.chrome.cast = cast;
 
 /**
  * If loaded within a page via a <script> element,
@@ -25,12 +25,12 @@ if (document.currentScript) {
 
     // Load Framework API if requested
     if (currentScriptParams.get("loadCastFramework") === "1") {
-        if (!global.cast) {
-            global.cast = {};
+        if (!_window.cast) {
+            _window.cast = {};
         }
 
         import("./framework").then(framework => {
-            global.cast.framework = framework.default;
+            _window.cast.framework = framework.default;
         });
     }
 }
@@ -42,7 +42,7 @@ onMessage(message => {
             const bridgeInfo = message.data;
 
             // Call page's API loaded function if defined
-            const readyFunction = global.__onGCastApiAvailable;
+            const readyFunction = _window.__onGCastApiAvailable;
             if (readyFunction && typeof readyFunction === "function") {
                 readyFunction(bridgeInfo && bridgeInfo.isVersionCompatible);
             }