Updated events example to reflect changes to button.

examples/widgets/Part 2 - Events.ipynb

@@ -110,7 +110,29 b''
      ],
      "language": "python",
      "metadata": {},
-     "outputs": [],
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "25\n"
+       ]
+      },
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "73\n"
+       ]
+      },
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "99\n"
+       ]
+      }
+     ],
      "prompt_number": 3
     },
     {
@@ -169,7 +191,7 b''
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "Button clicks are tracked by the `clicks` property of the button widget.  By using the `on_click` method and the `clicks` property, a button that outputs how many times it has been clicked is shown below."
+      "Button clicks are transmitted from the front-end to the back-end using custom messages.  By using the `on_click` method, a button that prints a message when it has been clicked is shown below."
      ]
     },
     {
@@ -180,7 +202,7 b''
       "display(button)\n",
       "\n",
       "def on_button_clicked(sender):\n",
-      "    print(\"Button clicked %d times.\" % sender.clicks)\n",
+      "    print(\"Button clicked.\")\n",
       "\n",
       "button.on_click(on_button_clicked)"
      ],
@@ -191,21 +213,21 b''
        "output_type": "stream",
        "stream": "stdout",
        "text": [
-        "Button clicked 1 times.\n"
+        "Button clicked.\n"
        ]
       },
       {
        "output_type": "stream",
        "stream": "stdout",
        "text": [
-        "Button clicked 2 times.\n"
+        "Button clicked.\n"
        ]
       },
       {
        "output_type": "stream",
        "stream": "stdout",
        "text": [
-        "Button clicked 3 times.\n"
+        "Button clicked.\n"
        ]
       }
      ],
@@ -224,7 +246,12 b''
      "input": [
       "def show_button(sender=None):\n",
       "    button = widgets.ButtonWidget()\n",
-      "    button.description = \"%d\" % (sender.clicks if sender is not None else 0)\n",
+      "    button.clicks = 0\n",
+      "    if sender is None:\n",
+      "        button.description = \"0\"\n",
+      "    else:\n",
+      "        sender.clicks += 1\n",
+      "        button.description = \"%d\" % sender.clicks\n",
       "    display(button)\n",
       "    button.on_click(show_button)\n",
       "show_button()\n",