diff --git a/playground.css b/playground.css
index 1046bcec..0e02cbdb 100644
--- a/playground.css
+++ b/playground.css
@@ -75,27 +75,30 @@ body {
   margin-top: 8px;
 }
 
-/* CONTENT ****************************************/
-.content {
+/* RIGHT PANE ****************************************/
+.right-pane {
   background-color: lightgray;
   overflow: hidden;
 }
 
-.content iframe {
+.right-pane iframe {
   background-color: white;
   width: 100%;
   height: 100%;
   border: 0;
 }
 
-.content .welcome {
+.content {
+  height: 100%;
+}
+.right-pane .welcome {
   text-align: center;
   font-size: 30px;
   color: gray;
   margin-top: 50px;
 }
 
-.content .url {
+.right-pane .url {
   font-size: 20px;
   margin-top: 20px;
 }
@@ -104,7 +107,15 @@ body {
   color: gray;
 }
 
-.content .note {
+.right-pane .note {
   font-size: 20px;
   margin-top: 20px;
 }
+
+.right-pane .error {
+  height: 100%;
+  padding-top: 40%;
+  font-size: 30px;
+  color: darkred;
+  text-align: center;
+}
diff --git a/src/playground.js b/src/playground.js
index 890e1622..a7f5fb20 100644
--- a/src/playground.js
+++ b/src/playground.js
@@ -8,13 +8,16 @@ const MODES = {
   xml: "ace/mode/xml"
 };
 
+const DEFAULT_XML = `<templates>
+</templates>`;
+
 const TEMPLATE = `
   <div class="playground">
       <div class="left-bar">
         <div class="menubar">
           <a class="tab" t-att-class="{active: state.currentTab==='js'}" t-on-click="setTab('js')">JS</a>
-          <a class="tab" t-att-class="{active: state.currentTab==='css'}" t-on-click="setTab('css')">CSS</a>
           <a class="tab" t-att-class="{active: state.currentTab==='xml'}" t-on-click="setTab('xml')">XML</a>
+          <a class="tab" t-att-class="{active: state.currentTab==='css'}" t-on-click="setTab('css')">CSS</a>
           <div class="right-thing">
             <select t-on-change="setSample">
               <option t-foreach="SAMPLES" t-as="sample">
@@ -26,13 +29,17 @@ const TEMPLATE = `
         </div>
         <div class="code-editor" t-ref="editor"></div>
       </div>
-      <div class="content" t-ref="content">
-        <div class="welcome">
+      <div class="right-pane">
+        <div class="welcome" t-if="state.displayWelcome">
           <div>🦉 Odoo Web Lab 🦉</div>
           <div>v<t t-esc="version"/></div>
           <div class="url"><a href="https://github.com/odoo/owl">https://github.com/odoo/owl</a></div>
           <div class="note">Note: these examples require a recent browser to work without a transpilation step. </div>
         </div>
+        <div t-if="state.error" class="error">
+          <t t-esc="state.error.message"/>
+        </div>
+        <div class="content" t-ref="content"/>
       </div>
   </div>`;
 
@@ -46,7 +53,9 @@ class Playground extends Component {
       currentTab: "js",
       js: SAMPLES[0].code,
       css: SAMPLES[0].css || "",
-      xml: ""
+      xml: SAMPLES[0].xml || DEFAULT_XML,
+      error: false,
+      displayWelcome: true
     };
   }
 
@@ -59,9 +68,24 @@ class Playground extends Component {
     this.editor.session.setMode("ace/mode/javascript");
   }
 
-  runCode() {
+  async runCode() {
     this.updateStateFromEditor();
 
+    // check templates
+    var qweb = new owl.core.QWeb();
+    var error = false;
+    try {
+      qweb.loadTemplates(this.state.xml);
+    } catch (e) {
+      error = e;
+    }
+
+    await this.updateState({ error, displayWelcome: false });
+    if (error) {
+      this.refs.content.innerHTML = "";
+      return;
+    }
+
     // create iframe
     const iframe = document.createElement("iframe");
 
@@ -74,7 +98,10 @@ class Playground extends Component {
       owlScript.addEventListener("load", () => {
         const script = doc.createElement("script");
         script.type = "text/javascript";
-        script.innerHTML = this.state.js;
+        const content = `window.TEMPLATES = \`${this.state.xml}\`\n${
+          this.state.js
+        }`;
+        script.innerHTML = content;
         doc.body.appendChild(script);
       });
       doc.head.appendChild(owlScript);
@@ -93,7 +120,7 @@ class Playground extends Component {
     this.updateState({
       js: sample.code,
       css: sample.css || "",
-      xml: ""
+      xml: sample.xml || DEFAULT_XML
     });
     this.editor.setValue(this.state[this.state.currentTab], -1);
   }
diff --git a/src/samples.js b/src/samples.js
index 97c7180e..5fe07339 100644
--- a/src/samples.js
+++ b/src/samples.js
@@ -1,7 +1,7 @@
 const HELLO_WORLD = `class HelloWorld extends owl.core.Component {
   constructor(...args) {
     super(...args);
-    this.inlineTemplate = \`<div>Hello <t t-esc="props.name"/></div>\`;
+    this.inlineTemplate = \`<div class="hello">Hello <t t-esc="props.name"/></div>\`;
   }
 }
 
@@ -13,9 +13,14 @@ const hello = new HelloWorld(env, { name: "World" });
 hello.mount(document.body);
 `;
 
+const HELLO_WORLD_CSS = `.hello {
+    color: darkred;
+    font-size: 30px;
+}`;
+
 const HELLO_WORLD_ESNEXT = `// This example will not work if your browser does not support ESNext Class Fields
 class HelloWorld extends owl.core.Component {
-  inlineTemplate = \`<div>Hello <t t-esc="props.name"/></div>\`;
+  inlineTemplate = \`<div class="hello">Hello <t t-esc="props.name"/></div>\`;
 }
 
 const env = {
@@ -99,12 +104,7 @@ for (let i = 1; i < 16000; i++) {
 class Counter extends owl.core.Component {
   constructor(parent, props) {
     super(parent, props);
-    this.inlineTemplate = \`
-      <div>
-        <button t-on-click="increment(-1)">-</button>
-        <span style="font-weight:bold">Value: <t t-esc="state.counter"/></span>
-        <button t-on-click="increment(1)">+</button>
-      </div>\`;
+    this.template = "counter";
     this.state = {
       counter: props.initialState || 0
     };
@@ -122,13 +122,7 @@ class Message extends owl.core.Component {
 
   constructor(parent, props) {
     super(parent, props);
-    this.inlineTemplate = \`
-      <div class="message">
-          <span class="author"><t t-esc="props.author"/></span>
-          <span class="msg"><t t-esc="props.msg"/></span>
-          <button class="remove" t-on-click="removeMessage">Remove</button>
-          <t t-widget="Counter" t-props="{initialState: props.id}"/>
-      </div>\`;
+    this.template = "message";
     this.widgets = { Counter };
   }
 
@@ -142,34 +136,10 @@ class Message extends owl.core.Component {
 //------------------------------------------------------------------------------
 // Root Widget
 //------------------------------------------------------------------------------
-const template = \`
-    <div class="main">
-        <div class="left-thing">
-            <div class="counter">
-                <button t-on-click="increment(-1)">-</button>
-                <span style="font-weight:bold">Value: <t t-esc="state.messages.length"/></span>
-                <button t-on-click="increment(1)">+</button>
-            </div>
-            <button t-on-click="setMessageCount(10)">10 messages</button>
-            <button t-on-click="setMessageCount(20)">20 messages</button>
-            <button t-on-click="setMessageCount(500)">500 messages</button>
-            <button t-on-click="setMessageCount(1000)">1000 messages</button>
-            <button t-on-click="setMessageCount(5000)">5000 messages</button>
-            <button t-on-click="setMessageCount(15000)">15000 messages</button>
-        </div>
-        <div class="right-thing">
-            <div class="content">
-                <t t-foreach="state.messages" t-as="message">
-                    <t t-widget="Message" t-att-key="message.id" t-props="message" t-on-remove_message="removeMessage"/>
-                </t>
-            </div>
-        </div>
-    </div>\`;
-
 class App extends owl.core.Component {
   constructor(parent, props) {
     super(parent, props);
-    this.inlineTemplate = template;
+    this.template = "root";
     this.widgets = { Message };
     this.state = {
       messages: messages.slice(0, 10)
@@ -198,9 +168,9 @@ class App extends owl.core.Component {
 //------------------------------------------------------------------------------
 // Application initialization
 //------------------------------------------------------------------------------
-const env = {
-    qweb: new owl.core.QWeb()
-};
+const qweb = new owl.core.QWeb();
+qweb.loadTemplates(TEMPLATES);
+const env = {qweb};
 
 const app = new App(env);
 app.mount(document.body);
@@ -252,6 +222,45 @@ const BENCHMARK_APP_CSS = `.main {
   padding: 5px;
 }`;
 
+const BENCHMARK_APP_XML = `<templates>
+  <div t-name="root" class="main">
+      <div class="left-thing">
+          <div class="counter">
+              <button t-on-click="increment(-1)">-</button>
+              <span style="font-weight:bold">Value: <t t-esc="state.messages.length"/></span>
+              <button t-on-click="increment(1)">+</button>
+          </div>
+          <button t-on-click="setMessageCount(10)">10 messages</button>
+          <button t-on-click="setMessageCount(20)">20 messages</button>
+          <button t-on-click="setMessageCount(500)">500 messages</button>
+          <button t-on-click="setMessageCount(1000)">1000 messages</button>
+          <button t-on-click="setMessageCount(5000)">5000 messages</button>
+          <button t-on-click="setMessageCount(15000)">15000 messages</button>
+      </div>
+      <div class="right-thing">
+          <div class="content">
+              <t t-foreach="state.messages" t-as="message">
+                  <t t-widget="Message" t-att-key="message.id" t-props="message" t-on-remove_message="removeMessage"/>
+              </t>
+          </div>
+      </div>
+  </div>
+
+  <div t-name="message" class="message">
+    <span class="author"><t t-esc="props.author"/></span>
+    <span class="msg"><t t-esc="props.msg"/></span>
+    <button class="remove" t-on-click="removeMessage">Remove</button>
+    <t t-widget="Counter" t-props="{initialState: props.id}"/>
+  </div>
+
+  <div t-name="counter">
+    <button t-on-click="increment(-1)">-</button>
+    <span style="font-weight:bold">Value: <t t-esc="state.counter"/></span>
+    <button t-on-click="increment(1)">+</button>
+  </div>
+
+</templates>`;
+
 const STATE_MANAGEMENT = `// todo`;
 
 const EMPTY = ``;
@@ -259,11 +268,13 @@ const EMPTY = ``;
 export const SAMPLES = [
   {
     description: "Hello World",
-    code: HELLO_WORLD
+    code: HELLO_WORLD,
+    css: HELLO_WORLD_CSS
   },
   {
     description: "Hello World (ESNext)",
-    code: HELLO_WORLD_ESNEXT
+    code: HELLO_WORLD_ESNEXT,
+    css: HELLO_WORLD_CSS
   },
   {
     description: "Widget Composition",
@@ -272,7 +283,8 @@ export const SAMPLES = [
   {
     description: "Benchmark application",
     code: BENCHMARK_APP,
-    css: BENCHMARK_APP_CSS
+    css: BENCHMARK_APP_CSS,
+    xml: BENCHMARK_APP_XML
   },
   {
     description: "State management app",