diff --git a/gallery/src/data/media_player_images/media_player.bedroom.jpg b/gallery/public/api/media_player_proxy/media_player.bedroom
similarity index 100%
rename from gallery/src/data/media_player_images/media_player.bedroom.jpg
rename to gallery/public/api/media_player_proxy/media_player.bedroom
diff --git a/gallery/src/data/media_player_images/media_player.living_room.jpg b/gallery/public/api/media_player_proxy/media_player.living_room
similarity index 100%
rename from gallery/src/data/media_player_images/media_player.living_room.jpg
rename to gallery/public/api/media_player_proxy/media_player.living_room
diff --git a/gallery/src/data/media_player_images/media_player.walkman.jpg b/gallery/public/api/media_player_proxy/media_player.walkman
similarity index 100%
rename from gallery/src/data/media_player_images/media_player.walkman.jpg
rename to gallery/public/api/media_player_proxy/media_player.walkman
diff --git a/gallery/src/components/demo-card.js b/gallery/src/components/demo-card.js
index 186584908f..83b0c51f4d 100644
--- a/gallery/src/components/demo-card.js
+++ b/gallery/src/components/demo-card.js
@@ -48,6 +48,10 @@ class DemoCard extends PolymerElement {
 
   static get properties() {
     return {
+      hass: {
+        type: Object,
+        observer: '_hassChanged',
+      },
       config: {
         type: Object,
         observer: '_configChanged'
@@ -62,17 +66,27 @@ class DemoCard extends PolymerElement {
       card.removeChild(card.lastChild);
     }
 
-    const hass = new HomeAssistant();
-    hass.config = demoConfig;
-    hass.resources = demoResources;
-    hass.language = 'en';
-    hass.states = demoStates;
-
     const el = createCardElement(JsYaml.safeLoad(config.config)[0]);
-    el.hass = hass;
+
+    if (this.hass) {
+      el.hass = this.hass;
+    } else {
+      const hass = new HomeAssistant(demoStates);
+      hass.config = demoConfig;
+      hass.resources = demoResources;
+      hass.language = 'en';
+      hass.states = demoStates;
+      el.hass = hass;
+    }
+
     card.appendChild(el);
   }
 
+  _hassChanged(hass) {
+    const card = this.$.card.lastChild;
+    if (card) card.hass = hass;
+  }
+
   _trim(config) {
     return config.trim();
   }
diff --git a/gallery/src/components/demo-cards.js b/gallery/src/components/demo-cards.js
index e71c2cf8e2..f4d6edf755 100644
--- a/gallery/src/components/demo-cards.js
+++ b/gallery/src/components/demo-cards.js
@@ -36,6 +36,7 @@ class DemoCards extends PolymerElement {
           <demo-card
             config='[[item]]'
             show-config='[[showConfig]]'
+            hass='[[hass]]'
           ></demo-card>
         </template>
       </div>
@@ -45,6 +46,7 @@ class DemoCards extends PolymerElement {
   static get properties() {
     return {
       configs: Object,
+      hass: Object,
       showConfig: {
         type: Boolean,
         value: false,
diff --git a/gallery/src/data/entity.js b/gallery/src/data/entity.js
new file mode 100644
index 0000000000..756354e0fa
--- /dev/null
+++ b/gallery/src/data/entity.js
@@ -0,0 +1,116 @@
+const now = () => new Date().toISOString();
+const randomTime = () =>
+  new Date(new Date().getTime() - (Math.random() * 80 * 60 * 1000)).toISOString();
+
+/* eslint-disable no-unused-vars */
+
+export class Entity {
+  constructor(domain, objectId, state, baseAttributes) {
+    this.domain = domain;
+    this.objectId = objectId;
+    this.entityId = `${domain}.${objectId}`;
+    this.lastChanged = randomTime();
+    this.lastUpdated = randomTime();
+    this.state = state;
+    // These are the attributes that we always write to the state machine
+    this.baseAttributes = baseAttributes;
+    this.attributes = baseAttributes;
+  }
+
+  async handleService(domain, service, data) {
+    console.log(`Unmocked service for ${this.entityId}: ${domain}/${service}`, data);
+  }
+
+  update(state, attributes = {}) {
+    this.state = state;
+    this.lastUpdated = now();
+    this.lastChanged = state === this.state ? this.lastChanged : this.lastUpdated;
+    this.attributes = Object.assign({}, this.baseAttributes, attributes);
+
+    console.log('update', this.entityId, this);
+
+    this.hass.updateStates({
+      [this.entityId]: this.toState()
+    });
+  }
+
+  toState() {
+    return {
+      entity_id: this.entityId,
+      state: this.state,
+      attributes: this.attributes,
+      last_changed: this.lastChanged,
+      last_updated: this.lastUpdated,
+    };
+  }
+}
+
+export class LightEntity extends Entity {
+  async handleService(domain, service, data) {
+    if (!['homeassistant', this.domain].includes(domain)) return;
+
+    if (service === 'turn_on') {
+      // eslint-disable-next-line
+      const { brightness, hs_color } = data;
+      this.update('on', Object.assign(this.attributes, {
+        brightness,
+        hs_color,
+      }));
+    } else if (service === 'turn_off') {
+      this.update('off');
+    } else if (service === 'toggle') {
+      if (this.state === 'on') {
+        this.handleService(domain, 'turn_off', data);
+      } else {
+        this.handleService(domain, 'turn_on', data);
+      }
+    }
+  }
+}
+
+export class LockEntity extends Entity {
+  async handleService(domain, service, data) {
+    if (domain !== this.domain) return;
+
+    if (service === 'lock') {
+      this.update('locked');
+    } else if (service === 'unlock') {
+      this.update('unlocked');
+    }
+  }
+}
+
+export class CoverEntity extends Entity {
+  async handleService(domain, service, data) {
+    if (domain !== this.domain) return;
+
+    if (service === 'open_cover') {
+      this.update('open');
+    } else if (service === 'close_cover') {
+      this.update('closing');
+    }
+  }
+}
+
+export class GroupEntity extends Entity {
+  async handleService(domain, service, data) {
+    if (!['homeassistant', this.domain].includes(domain)) return;
+
+    await Promise.all(this.attributes.entity_id.map((ent) => {
+      const entity = this.hass.mockEntities[ent];
+      return entity.handleService(entity.domain, service, data);
+    }));
+
+    this.update(service === 'turn_on' ? 'on' : 'off');
+  }
+}
+
+const TYPES = {
+  light: LightEntity,
+  lock: LockEntity,
+  cover: CoverEntity,
+  group: GroupEntity,
+};
+
+export default (domain, objectId, state, baseAttributes = {}) =>
+  new (TYPES[domain] || Entity)(domain, objectId, state, baseAttributes);
diff --git a/gallery/src/data/hass.js b/gallery/src/data/hass.js
index 59179d6637..918132af4c 100644
--- a/gallery/src/data/hass.js
+++ b/gallery/src/data/hass.js
@@ -1,6 +1,6 @@
 export default class FakeHass {
-  constructor() {
-    this.states = {};
+  constructor(states = {}) {
+    this.states = states;
     this._wsCommands = {};
   }
 
diff --git a/gallery/src/data/provide_hass.js b/gallery/src/data/provide_hass.js
new file mode 100644
index 0000000000..8ebadb022b
--- /dev/null
+++ b/gallery/src/data/provide_hass.js
@@ -0,0 +1,79 @@
+import fireEvent from '../../../src/common/dom/fire_event.js';
+
+import demoConfig from './demo_config.js';
+import demoResources from './demo_resources.js';
+
+const ensureArray = val => (Array.isArray(val) ? val : [val]);
+
+export default (elements, { initialStates = {} } = {}) => {
+  elements = ensureArray(elements);
+
+  const wsCommands = {};
+  let hass;
+  const entities = {};
+
+  function updateHass(obj) {
+    hass = Object.assign({}, hass, obj);
+    elements.forEach((el) => { el.hass = hass; });
+  }
+
+  updateHass({
+    // Home Assistant properties
+    config: demoConfig,
+    language: 'en',
+    resources: demoResources,
+    states: initialStates,
+
+    // Mock properties
+    mockEntities: entities,
+
+    // Home Assistant functions
+    async callService(domain, service, data) {
+      fireEvent(elements[0], 'show-notification', { message: `Called service ${domain}/${service}` });
+      if (data.entity_id) {
+        await Promise.all(ensureArray(data.entity_id).map(ent =>
+          entities[ent].handleService(domain, service, data)));
+      } else {
+        console.log('unmocked callService', domain, service, data);
+      }
+    },
+
+    async callWS(msg) {
+      const callback = wsCommands[msg.type];
+      return callback ? callback(msg) : Promise.reject({
+        code: 'command_not_mocked',
+        message: 'This command is not implemented in the gallery.',
+      });
+    },
+
+    async sendWS(msg) {
+      const callback = wsCommands[msg.type];
+
+      if (callback) {
+        callback(msg);
+      } else {
+        console.error(`Unknown command: ${msg.type}`);
+      }
+      console.log('sendWS', msg);
+    },
+
+    // Mock functions
+    updateHass,
+    updateStates(newStates) {
+      updateHass({
+        states: Object.assign({}, hass.states, newStates),
+      });
+    },
+    addEntities(newEntities) {
+      const states = {};
+      ensureArray(newEntities).forEach((ent) => {
+        ent.hass = hass;
+        entities[ent.entityId] = ent;
+        states[ent.entityId] = ent.toState();
+      });
+      this.updateStates(states);
+    }
+  });
+
+  return hass;
+};
diff --git a/gallery/src/demos/demo-hui-entities-card.js b/gallery/src/demos/demo-hui-entities-card.js
index bd4d73cdc1..f473b01bb9 100644
--- a/gallery/src/demos/demo-hui-entities-card.js
+++ b/gallery/src/demos/demo-hui-entities-card.js
@@ -1,8 +1,45 @@
 import { html } from '@polymer/polymer/lib/utils/html-tag.js';
 import { PolymerElement } from '@polymer/polymer/polymer-element.js';
 
+import getEntity from '../data/entity.js';
+import provideHass from '../data/provide_hass.js';
 import '../components/demo-cards.js';
 
+const ENTITIES = [
+  getEntity('light', 'bed_light', 'on', {
+    friendly_name: 'Bed Light'
+  }),
+  getEntity('group', 'kitchen', 'on', {
+    entity_id: [
+      'light.bed_light',
+    ],
+    order: 8,
+    friendly_name: 'Kitchen'
+  }),
+  getEntity('lock', 'kitchen_door', 'locked', {
+    friendly_name: 'Kitchen Door'
+  }),
+  getEntity('cover', 'kitchen_window', 'open', {
+    friendly_name: 'Kitchen Window',
+    supported_features: 11
+  }),
+  getEntity('scene', 'romantic_lights', 'scening', {
+    entity_id: [
+      'light.bed_light',
+      'light.ceiling_lights'
+    ],
+    friendly_name: 'Romantic lights'
+  }),
+  getEntity('device_tracker', 'demo_paulus', 'home', {
+    source_type: 'gps',
+    latitude: 32.877105,
+    longitude: 117.232185,
+    gps_accuracy: 91,
+    battery: 71,
+    friendly_name: 'Paulus'
+  }),
+];
+
 const CONFIGS = [
   {
     heading: 'Basic',
@@ -48,7 +85,7 @@ const CONFIGS = [
     `
   },
   {
-    heading: 'With title, cant\'t toggle',
+    heading: 'With title, can\'t toggle',
     config: `
 - type: entities
   entities:
@@ -80,7 +117,11 @@ const CONFIGS = [
 class DemoEntities extends PolymerElement {
   static get template() {
     return html`
-      <demo-cards configs="[[_configs]]"></demo-cards>
+      <demo-cards
+        id='demos'
+        hass='[[hass]]'
+        configs="[[_configs]]"
+      ></demo-cards>
     `;
   }
 
@@ -89,9 +130,16 @@ class DemoEntities extends PolymerElement {
       _configs: {
         type: Object,
         value: CONFIGS
-      }
+      },
+      hass: Object,
     };
   }
+
+  ready() {
+    super.ready();
+    const hass = provideHass(this.$.demos);
+    hass.addEntities(ENTITIES);
+  }
 }
 
 customElements.define('demo-hui-entities-card', DemoEntities);
diff --git a/gallery/src/ha-gallery.js b/gallery/src/ha-gallery.js
index fbcd9fc943..d09dd5e0d7 100644
--- a/gallery/src/ha-gallery.js
+++ b/gallery/src/ha-gallery.js
@@ -9,6 +9,8 @@ import '@polymer/paper-icon-button/paper-icon-button.js';
 import { html } from '@polymer/polymer/lib/utils/html-tag.js';
 import { PolymerElement } from '@polymer/polymer/polymer-element.js';
 
+import '../../src/managers/notification-manager.js';
+
 const demos = require.context('./demos', true, /^(.*\.(js$))[^.]*$/im);
 
 const fixPath = path => path.substr(2, path.length - 5);
@@ -91,6 +93,7 @@ class HaGallery extends PolymerElement {
           </template>
         </div>
       </app-header-layout>
+      <notification-manager id='notifications'></notification-manager>
     `;
   }
 
@@ -111,8 +114,15 @@ class HaGallery extends PolymerElement {
   ready() {
     super.ready();
 
+    this.addEventListener(
+      'show-notification',
+      ev => this.$.notifications.showNotification(ev.detail.message)
+    );
+
     this.addEventListener('hass-more-info', (ev) => {
-      if (ev.detail.entityId) alert(`Showing more info for ${ev.detail.entityId}`);
+      if (ev.detail.entityId) {
+        this.$.notifications.showNotification(`Showing more info for ${ev.detail.entityId}`);
+      }
     });
 
     window.addEventListener('hashchange', () => { this._demo = document.location.hash.substr(1); });
diff --git a/gallery/webpack.config.js b/gallery/webpack.config.js
index 91f782c155..31ced8cfcb 100644
--- a/gallery/webpack.config.js
+++ b/gallery/webpack.config.js
@@ -49,12 +49,11 @@ module.exports = {
   plugins: [
     new CopyWebpackPlugin([
       'public',
+      { from: '../public', to: 'static' },
+      { from: '../build-translations/output', to: 'static/translations' },
       { from: '../node_modules/leaflet/dist/leaflet.css', to: 'static/images/leaflet/' },
       { from: '../node_modules/@polymer/font-roboto-local/fonts', to: 'static/fonts' },
       { from: '../node_modules/leaflet/dist/images', to: 'static/images/leaflet/' },
-      { from: './src/data/media_player_images/media_player.bedroom.jpg', to: 'api/media_player_proxy/media_player.bedroom' },
-      { from: './src/data/media_player_images/media_player.living_room.jpg', to: 'api/media_player_proxy/media_player.living_room' },
-      { from: './src/data/media_player_images/media_player.walkman.jpg', to: 'api/media_player_proxy/media_player.walkman' },
     ]),
     isProd && new UglifyJsPlugin({
       extractComments: true,
diff --git a/src/managers/notification-manager.js b/src/managers/notification-manager.js
index c55eff9347..a3820862df 100644
--- a/src/managers/notification-manager.js
+++ b/src/managers/notification-manager.js
@@ -13,7 +13,7 @@ class NotificationManager extends LocalizeMixin(PolymerElement) {
       }
     </style>
 
-    <paper-toast id="toast" text="[[_text]]" no-cancel-on-outside-click="[[_cancelOnOutsideClick]]"></paper-toast>
+    <paper-toast id="toast" no-cancel-on-outside-click="[[_cancelOnOutsideClick]]"></paper-toast>
     <paper-toast id="connToast" duration="0" text="[[localize('ui.notification_toast.connection_lost')]]" opened="[[connectionLost]]"></paper-toast>
 `;
   }
@@ -40,11 +40,6 @@ class NotificationManager extends LocalizeMixin(PolymerElement) {
         value: false,
       },
 
-      _text: {
-        type: String,
-        readOnly: true,
-      },
-
       toastClass: {
         type: String,
         value: '',
@@ -90,8 +85,7 @@ class NotificationManager extends LocalizeMixin(PolymerElement) {
   }
 
   showNotification(message) {
-    this._set_text(message);
-    this.$.toast.show();
+    this.$.toast.show(message);
   }
 }