diff --git a/examples/Interactive Widgets/Widget Styling.ipynb b/examples/Interactive Widgets/Widget Styling.ipynb
index 136ae87..c9fce87 100644
--- a/examples/Interactive Widgets/Widget Styling.ipynb
+++ b/examples/Interactive Widgets/Widget Styling.ipynb
@@ -7,7 +7,7 @@
    ]
   ],
   "name": "",
-  "signature": "sha256:cd7d3d42126bdbf20c087014460779dfbdb0a63dcb8f489ba7ebfc230a685edd"
+  "signature": "sha256:55ee4a4661f0939c40550752218a4c127b985536811190a2b7e581d7fe25cec7"
  },
  "nbformat": 3,
  "nbformat_minor": 0,
@@ -18,243 +18,865 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "from IPython.html import widgets # Widget definitions\n",
-      "from IPython.display import display # Used to display widgets in the notebook"
+      "%%html\n",
+      "<style>\n",
+      ".example-container { background: #999999; padding: 2px; min-height: 100px; }\n",
+      ".example-container.sm { min-height: 50px; }\n",
+      ".example-box { background: #9999FF; width: 50px; height: 50px; text-align: center; vertical-align: middle; color: white; font-weight: bold; margin: 2px;}\n",
+      ".example-box.med { width: 65px; height: 65px; }   \n",
+      ".example-box.lrg { width: 80px; height: 80px; }   \n",
+      "</style>"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "html": [
+        "<style>\n",
+        ".example-container { background: #999999; padding: 2px; min-height: 100px; }\n",
+        ".example-container.sm { min-height: 50px; }\n",
+        ".example-box { background: #9999FF; width: 50px; height: 50px; text-align: center; vertical-align: middle; color: white; font-weight: bold; margin: 2px;}\n",
+        ".example-box.med { width: 65px; height: 65px; }   \n",
+        ".example-box.lrg { width: 80px; height: 80px; }   \n",
+        "</style>"
+       ],
+       "metadata": {},
+       "output_type": "display_data",
+       "text": [
+        "<IPython.core.display.HTML object>"
+       ]
+      }
+     ],
+     "prompt_number": 145
+    },
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "CSS"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Since the representation of the widget you see is a browser element, Cascading Style Sheets (CSS) are used for styling.  Widgets have a `set_css` method that allows you to add and remove CSS properties from your elements.  The following example shows had `set_css` can be used to set the background color of a `TextWidget`."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "from IPython.html import widgets\n",
+      "text = widgets.TextWidget()\n",
+      "text.set_css('background', 'lime')\n",
+      "text "
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 146
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "In the example above, the color `lime` is specified by name.  CSS also supports specifying colors by a 3 byte hexadecimal string.  The first byte is red, second green, and third blue.  The following example sets the `TextWidget`'s background to blue."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "text.set_css('background', '#0000FF')"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 147
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Font color is just `color`."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "text.set_css('color', '#FFFFFF')"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 148
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "To remove the styling, you can call `set_css` again, but use an empty string instead of a color value."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "text.set_css('background', '')"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 149
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "CSS is also used to set the height and width of controls.  The `set_css` method also can accept a single dictionary with multiple CSS properties (as seen below)."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "btn = widgets.ButtonWidget()\n",
+      "btn.set_css({\n",
+      "    'width': '100px',\n",
+      "    'height': '100px',\n",
+      "})\n",
+      "btn"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 150
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "For more information about what can be done with CSS, please refer to the [Mozilla Developer Network's series on it](https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Getting_started).\n"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Parent/Child Relationships"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "To display widget A inside widget B, widget A must be a child of widget B.  Only one instance of any particular widget can be child of another.  In other words, *widget A* cannot have *widget B* listed twice in it's list of children.\n",
+      "\n",
+      "Widgets that can contain other widgets have a `children` attribute.  This attribute can be set via a kwarg in the widget's constructor or after construction.  Calling display on an object with children automatically displays those children, too."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from IPython.display import display\n",
+      "\n",
+      "float_range = widgets.FloatSliderWidget()\n",
+      "string = widgets.TextWidget(value='hi')\n",
+      "container = widgets.ContainerWidget(children=[float_range, string])\n",
+      "\n",
+      "container.set_css('border', '3px dotted red')\n",
+      "display(container) # Displays the `container` and all of it's children."
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 151
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Children can also be added to parents after the parent has been displayed.  The parent is responsible for rendering its children."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "container = widgets.ContainerWidget()\n",
+      "container.set_css('border', '3px dotted red')\n",
+      "display(container)\n",
+      "\n",
+      "int_range = widgets.IntSliderWidget()\n",
+      "container.children=[int_range]"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 152
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Fancy containers"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "If you need to display a more complicated set of widgets, there are specialized containers that you can use.  To display multiple sets of widgets, you can use an `AccordionWidget` or a `TabWidget` in combination with one `ContainerWidget` per set of widgets (as seen below).  The \"pages\" of these widgets are their children.  To set the titles of the pages, one must call `set_title` after the widget has been displayed."
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 3,
+     "metadata": {},
+     "source": [
+      "AccordionWidget"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "name1 = widgets.TextWidget(description='Location:')\n",
+      "zip1 = widgets.BoundedIntTextWidget(description='Zip:', min=0, max=99999)\n",
+      "page1 = widgets.ContainerWidget(children=[name1, zip1])\n",
+      "\n",
+      "name2 = widgets.TextWidget(description='Location:')\n",
+      "zip2 = widgets.BoundedIntTextWidget(description='Zip:', min=0, max=99999)\n",
+      "page2 = widgets.ContainerWidget(children=[name2, zip2])\n",
+      "\n",
+      "accord = widgets.AccordionWidget(children=[page1, page2])\n",
+      "display(accord)\n",
+      "\n",
+      "accord.set_title(0, 'From')\n",
+      "accord.set_title(1, 'To')"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 153
+    },
+    {
+     "cell_type": "heading",
+     "level": 3,
+     "metadata": {},
+     "source": [
+      "TabWidget"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "name = widgets.TextWidget(description='Name:')\n",
+      "color = widgets.DropdownWidget(description='Color:', values=['red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet'])\n",
+      "page1 = widgets.ContainerWidget(children=[name, color])\n",
+      "\n",
+      "age = widgets.IntSliderWidget(description='Age:', min=0, max=120, value=50)\n",
+      "gender = widgets.RadioButtonsWidget(description='Gender:', values=['male', 'female'])\n",
+      "page2 = widgets.ContainerWidget(children=[age, gender])\n",
+      "\n",
+      "tabs = widgets.TabWidget(children=[page1, page2])\n",
+      "display(tabs)\n",
+      "\n",
+      "tabs.set_title(0, 'Name')\n",
+      "tabs.set_title(1, 'Details')"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 154
+    },
+    {
+     "cell_type": "heading",
+     "level": 3,
+     "metadata": {},
+     "source": [
+      "PopupWidget"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Unlike the other two special containers, the `PopupWidget` is only designed to display one set of widgets.  The `PopupWidget` can be used to display widgets outside of the widget area.  "
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "counter = widgets.IntTextWidget(description='Counter:')\n",
+      "popup = widgets.PopupWidget(children=[counter], description='Popup Demo', button_text='Popup Button')\n",
+      "display(popup)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 155
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "counter.value += 1"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 156
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "counter.value += 1"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 157
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "popup.close()"
      ],
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 1
+     "prompt_number": 158
     },
     {
      "cell_type": "heading",
      "level": 1,
      "metadata": {},
      "source": [
-      "CSS"
+      "Alignment"
      ]
     },
     {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "When trying to design an attractive widget GUI, styling becomes important.\n",
-      "Most widget views are DOM (document object model) elements that can be controlled with CSS.\n",
-      "There are two helper methods that allow the manipulation of the widget's CSS.\n",
-      "The first is the `Widget.set_css` method.\n",
-      "This method allows one or more CSS attributes to be set at once.  "
+      "Most widgets have a `description` attribute, which allows a label for the widget to be defined.\n",
+      "The label of the widget has a fixed minimum width.\n",
+      "The text of the label is always right aligned and the widget is left aligned:"
      ]
     },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "print(widgets.DOMWidget.set_css.__doc__)"
+      "display(widgets.TextWidget(description=\"a:\"))\n",
+      "display(widgets.TextWidget(description=\"aa:\"))\n",
+      "display(widgets.TextWidget(description=\"aaa:\"))"
      ],
      "language": "python",
      "metadata": {},
-     "outputs": [
-      {
-       "output_type": "stream",
-       "stream": "stdout",
-       "text": [
-        "Set one or more CSS properties of the widget.\n",
-        "\n",
-        "        This function has two signatures:\n",
-        "        - set_css(css_dict, selector='')\n",
-        "        - set_css(key, value, selector='')\n",
-        "\n",
-        "        Parameters\n",
-        "        ----------\n",
-        "        css_dict : dict\n",
-        "            CSS key/value pairs to apply\n",
-        "        key: unicode\n",
-        "            CSS key\n",
-        "        value:\n",
-        "            CSS value\n",
-        "        selector: unicode (optional, kwarg only)\n",
-        "            JQuery selector to use to apply the CSS key/value.  If no selector \n",
-        "            is provided, an empty selector is used.  An empty selector makes the \n",
-        "            front-end try to apply the css to a default element.  The default\n",
-        "            element is an attribute unique to each view, which is a DOM element\n",
-        "            of the view that should be styled with common CSS (see \n",
-        "            `$el_to_style` in the Javascript code).\n",
-        "        \n"
-       ]
-      }
-     ],
-     "prompt_number": 2
+     "outputs": [],
+     "prompt_number": 159
     },
     {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "The second is `get_css` which allows CSS attributesto be read.\n",
-      "Note that this method will only read CSS attributes that have been set using the `set_css` method."
+      "If a label is longer than the minimum width, the widget is shifted to the right:"
      ]
     },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "print(widgets.DOMWidget.get_css.__doc__)"
+      "display(widgets.TextWidget(description=\"a:\"))\n",
+      "display(widgets.TextWidget(description=\"aa:\"))\n",
+      "display(widgets.TextWidget(description=\"aaa:\"))\n",
+      "display(widgets.TextWidget(description=\"aaaaaaaaaaaaaaaaaa:\"))"
      ],
      "language": "python",
      "metadata": {},
-     "outputs": [
-      {
-       "output_type": "stream",
-       "stream": "stdout",
-       "text": [
-        "Get a CSS property of the widget.\n",
-        "\n",
-        "        Note: This function does not actually request the CSS from the \n",
-        "        front-end;  Only properties that have been set with set_css can be read.\n",
-        "\n",
-        "        Parameters\n",
-        "        ----------\n",
-        "        key: unicode\n",
-        "            CSS key\n",
-        "        selector: unicode (optional)\n",
-        "            JQuery selector used when the CSS key/value was set.\n",
-        "        \n"
-       ]
-      }
-     ],
-     "prompt_number": 3
+     "outputs": [],
+     "prompt_number": 160
     },
     {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "Below is an example that applies CSS attributes to a container to emphasize text."
+      "If a `description` is not set for the widget, the label is not displayed:"
      ]
     },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "label = widgets.LatexWidget()\n",
-      "label.value = \"$\\\\textbf{ALERT:} Hello World!$\"\n",
-      "container = widgets.ContainerWidget(children=[label])\n",
-      "\n",
-      "# set_css used to set a single CSS attribute.\n",
-      "container.set_css('border', '3px solid black') # Border the container\n",
-      "\n",
-      "# set_css used to set multiple CSS attributes.\n",
-      "container.set_css({'padding': '6px', # Add padding to the container\n",
-      "                   'background': 'yellow'}) # Fill the container yellow\n",
-      "\n",
-      "display(container)"
+      "display(widgets.TextWidget(description=\"a:\"))\n",
+      "display(widgets.TextWidget(description=\"aa:\"))\n",
+      "display(widgets.TextWidget(description=\"aaa:\"))\n",
+      "display(widgets.TextWidget())"
      ],
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 4
+     "prompt_number": 161
     },
     {
      "cell_type": "heading",
      "level": 1,
      "metadata": {},
      "source": [
-      "CSS Classes"
+      "DOM Classes"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "IPython defines a large number of DOM (document object model) classes that you can apply to your widgets.  Applying a DOM class causes all of the CSS associated with that class to be applied to the element.  Classes can be applied and removed using the `add_class` and `remove_class` methods after a widget has been displayed.  The majority of DOM classes defined by IPython are actually Bootstrap classes.  For more information on Bootstrap classes and CSS, please refer to [Bootstrap's website](http://getbootstrap.com/2.3.2/)."
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Path dependent"
      ]
     },
     {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "In some cases, it is necessary to apply CSS classes to your widgets.\n",
-      "CSS classes allow DOM elements to be indentified in Javascript and CSS.\n",
-      "The notebook defines its own set of classes to stylize its elements.\n",
-      "The `add_class` widget method allows you to add CSS classes to your widget."
+      "Both `add_class` and `remove_class` allow you to use CSS selectors to pick which sub elements of your widget get styled.  Because of this, the `add_class` and `remove_class` methods are path dependent (order specific).  The following example shows the same three calls made in three different orders and the resulting output.  All three differ."
      ]
     },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "print(widgets.DOMWidget.add_class.__doc__)"
+      "%%html\n",
+      "<style>\n",
+      "    div.cube { display: inline; padding: 5px; }\n",
+      "    div.red { background: red; }\n",
+      "    div.blue { background: blue; }\n",
+      "</style>"
      ],
      "language": "python",
      "metadata": {},
      "outputs": [
       {
-       "output_type": "stream",
-       "stream": "stdout",
+       "html": [
+        "<style>\n",
+        "    div.cube { display: inline; padding: 5px; }\n",
+        "    div.red { background: red; }\n",
+        "    div.blue { background: blue; }\n",
+        "</style>"
+       ],
+       "metadata": {},
+       "output_type": "display_data",
        "text": [
-        "Add class[es] to a DOM element.\n",
-        "\n",
-        "        Parameters\n",
-        "        ----------\n",
-        "        class_names: unicode or list\n",
-        "            Class name(s) to add to the DOM element(s).\n",
-        "        selector: unicode (optional)\n",
-        "            JQuery selector to select the DOM element(s) that the class(es) will\n",
-        "            be added to.\n",
-        "        \n"
+        "<IPython.core.display.HTML object>"
        ]
       }
      ],
-     "prompt_number": 5
+     "prompt_number": 162
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "from IPython.html import widgets\n",
+      "from IPython.display import display\n",
+      "html = '<br />'.join([''.join(['<div class=\"cube\">x</div>' for i in range(8)]) for j in range(8)])\n",
+      "widget = [widgets.HTMLWidget(value=html) for i in range(3)]\n",
+      "\n",
+      "display(widget[0])\n",
+      "widget[0].add_class('red', 'div.cube:nth-child(even)')\n",
+      "widget[0].remove_class('red', 'div.red:nth-child(7n+1)')\n",
+      "widget[0].add_class('blue', 'div.red:nth-child(3n+1)')"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 163
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "display(widget[1])\n",
+      "widget[1].remove_class('red', 'div.red:nth-child(7n+1)')\n",
+      "widget[1].add_class('blue', 'div.red:nth-child(3n+1)')\n",
+      "widget[1].add_class('red', 'div.cube:nth-child(even)')"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 164
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "display(widget[2])\n",
+      "widget[2].add_class('red', 'div.cube:nth-child(even)')\n",
+      "widget[2].add_class('blue', 'div.red:nth-child(3n+1)')\n",
+      "widget[2].remove_class('red', 'div.red:nth-child(7n+1)')"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 165
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Alignment classes"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Widgets can be aligned using IPython specific alignment classes.  These classes should work with most widgets, but were designed to be applied to `ContainerWidget`s.  Examples of these classes follow:\n",
+      "\n",
+      "### Orientation classes\n",
+      "#### \"vbox\"\n",
+      "Widget containers default to this orientation.\n",
+      "<div class=\"example-container vbox\">\n",
+      "<div class=\"example-box\">A</div>\n",
+      "<div class=\"example-box med\">B</div>\n",
+      "<div class=\"example-box lrg\">C</div>\n",
+      "</div>\n",
+      "\n",
+      "#### \"hbox\"\n",
+      "<div class=\"example-container hbox\">\n",
+      "<div class=\"example-box\">A</div>\n",
+      "<div class=\"example-box med\">B</div>\n",
+      "<div class=\"example-box lrg\">C</div>\n",
+      "</div>\n",
+      "\n",
+      "### Packing classes\n",
+      "These examples use the hbox layout to show packing.  Packing is the alignment of the widgets along the the axis that they are displayed on.\n",
+      "#### \"start\"\n",
+      "<div class=\"example-container hbox start\">\n",
+      "<div class=\"example-box\">A</div>\n",
+      "<div class=\"example-box med\">B</div>\n",
+      "<div class=\"example-box lrg\">C</div>\n",
+      "</div>\n",
+      "\n",
+      "#### \"center\"\n",
+      "<div class=\"example-container hbox center\">\n",
+      "<div class=\"example-box\">A</div>\n",
+      "<div class=\"example-box med\">B</div>\n",
+      "<div class=\"example-box lrg\">C</div>\n",
+      "</div>\n",
+      "\n",
+      "#### \"end\"\n",
+      "<div class=\"example-container hbox end\">\n",
+      "<div class=\"example-box\">A</div>\n",
+      "<div class=\"example-box med\">B</div>\n",
+      "<div class=\"example-box lrg\">C</div>\n",
+      "</div>\n",
+      "\n",
+      "### Aligning classes\n",
+      "These examples use the hbox layout to show alignment.  Packing is the alignment of the widgets along the the axis perpindicular to the one that they are displayed on.\n",
+      "#### \"align-start\"\n",
+      "<div class=\"example-container hbox align-start\">\n",
+      "<div class=\"example-box\">A</div>\n",
+      "<div class=\"example-box med\">B</div>\n",
+      "<div class=\"example-box lrg\">C</div>\n",
+      "</div>\n",
+      "\n",
+      "#### \"align-center\"\n",
+      "<div class=\"example-container hbox align-center\">\n",
+      "<div class=\"example-box\">A</div>\n",
+      "<div class=\"example-box med\">B</div>\n",
+      "<div class=\"example-box lrg\">C</div>\n",
+      "</div>\n",
+      "\n",
+      "#### \"align-end\"\n",
+      "<div class=\"example-container hbox align-end\">\n",
+      "<div class=\"example-box\">A</div>\n",
+      "<div class=\"example-box med\">B</div>\n",
+      "<div class=\"example-box lrg\">C</div>\n",
+      "</div>\n",
+      "\n",
+      "### Flex classes\n",
+      "To specify how \"greedy\" a container is when filling in the remaining space of its parent, the `box-flexN` properties are used (where N is 0, 1, or 2).  The higher the value of N, the more greedy the child is.  `box-flex0` is the default behavior, which is to not fill the parent.\n",
+      "\n",
+      "#### Example 1\n",
+      "<div class=\"example-container sm hbox center\">\n",
+      "<div class=\"example-box box-flex0\">box-flex0</div>\n",
+      "<div class=\"example-box box-flex0\">box-flex0</div>\n",
+      "<div class=\"example-box box-flex0\">box-flex0</div>\n",
+      "</div>\n",
+      "\n",
+      "#### Example 2\n",
+      "<div class=\"example-container sm hbox center\">\n",
+      "<div class=\"example-box box-flex0\">box-flex0</div>\n",
+      "<div class=\"example-box box-flex1\">box-flex1</div>\n",
+      "<div class=\"example-box box-flex0\">box-flex0</div>\n",
+      "</div>\n",
+      "\n",
+      "#### Example 3\n",
+      "<div class=\"example-container sm hbox center\">\n",
+      "<div class=\"example-box box-flex0\">box-flex0</div>\n",
+      "<div class=\"example-box box-flex1\">box-flex1</div>\n",
+      "<div class=\"example-box box-flex1\">box-flex1</div>\n",
+      "</div>\n",
+      "\n",
+      "#### Example 4\n",
+      "<div class=\"example-container sm hbox center\">\n",
+      "<div class=\"example-box box-flex1\">box-flex1</div>\n",
+      "<div class=\"example-box box-flex1\">box-flex1</div>\n",
+      "<div class=\"example-box box-flex1\">box-flex1</div>\n",
+      "</div>\n",
+      "\n",
+      "#### Example 5\n",
+      "<div class=\"example-container sm hbox center\">\n",
+      "<div class=\"example-box box-flex2\">box-flex2</div>\n",
+      "<div class=\"example-box box-flex1\">box-flex1</div>\n",
+      "<div class=\"example-box box-flex1\">box-flex1</div>\n",
+      "</div>\n",
+      "\n",
+      "#### Example 6\n",
+      "<div class=\"example-container sm hbox center\">\n",
+      "<div class=\"example-box box-flex0\">box-flex0</div>\n",
+      "<div class=\"example-box box-flex1\">box-flex1</div>\n",
+      "<div class=\"example-box box-flex2\">box-flex2</div>\n",
+      "</div>\n"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 3,
+     "metadata": {},
+     "source": [
+      "Application to widgets"
+     ]
     },
     {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "Since `add_class` is a DOM operation, **it will only affect widgets that have already been displayed**.\n",
-      "`add_class` must be called after the widget has been displayed.\n",
-      "Extending the example above, the corners of the container can be rounded by adding the `corner-all` CSS class to the container."
+      "Widget containers default as vertical boxes."
      ]
     },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "container = widgets.ContainerWidget()\n",
-      "container.set_css({'border': '3px solid black',\n",
-      "                   'padding': '6px', \n",
-      "                   'background': 'yellow'}) \n",
+      "buttons = [widgets.ButtonWidget(description=str(i)) for i in range(3)]\n",
       "\n",
-      "label = widgets.LatexWidget()\n",
-      "label.value = \"$\\\\textbf{ALERT:} Hello World!$\"\n",
-      "container.children = [label]\n",
+      "container = widgets.ContainerWidget(children=buttons)\n",
+      "display(container)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 166
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "To make a widget container display its widgets horizontally, you need to remove the `vbox` class from the container and add the `hbox` class in its place."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "container = widgets.ContainerWidget(children=buttons)\n",
       "display(container)\n",
-      "container.add_class('corner-all') # Must be called AFTER display"
+      "container.remove_class('vbox')\n",
+      "container.add_class('hbox')"
      ],
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 6
+     "prompt_number": 167
     },
     {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "The IPython notebook uses [bootstrap](http://getbootstrap.com/\u200e) for styling.\n",
-      "The example above can be simplified by using a bootstrap class:"
+      "By setting the width of the container to 100% and adding the `center` class to it, you can center the buttons."
      ]
     },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "label = widgets.LatexWidget(value = \"$\\\\textbf{ALERT:} Hello World!$\")\n",
-      "display(label)\n",
-      "\n",
-      "# Apply twitter bootstrap alert class to the label.\n",
-      "label.add_class(\"alert\")"
+      "container.set_css('width', '100%')\n",
+      "container.add_class('center')"
      ],
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 7
+     "prompt_number": 168
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Style classes"
+     ]
     },
     {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "The example below shows how bootstrap classes can be used to change button apearance."
+      "In addition to alignment classes, the classes defined by Bootstrap can also be used.  This tutorial will only cover a few of the most common classes.  For a full list of Bootstrap classes, please refer to [Bootstrap's website](http://getbootstrap.com/2.3.2/)."
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 3,
+     "metadata": {},
+     "source": [
+      "ButtonWidgets"
      ]
     },
     {
@@ -262,91 +884,189 @@
      "collapsed": false,
      "input": [
       "# List of the bootstrap button styles\n",
-      "button_classes = ['Default', 'btn-primary', 'btn-info', 'btn-success', \n",
-      "                  'btn-warning', 'btn-danger', 'btn-inverse', 'btn-link']\n",
+      "classes = [\n",
+      "    'btn', \n",
+      "    'btn-primary', \n",
+      "    'btn-info', \n",
+      "    'btn-success', \n",
+      "    'btn-warning', \n",
+      "    'btn-danger', \n",
+      "    'btn-inverse', \n",
+      "    'btn-link'\n",
+      "]\n",
+      "\n",
+      "# Display the buttons in a hbox\n",
+      "container = widgets.ContainerWidget(children=[widgets.ButtonWidget(description=c) for c in classes])\n",
+      "display(container)\n",
+      "\n",
+      "# Apply classes after display\n",
+      "container.remove_class('vbox')\n",
+      "container.add_class('hbox')\n",
+      "ret = [container.children[i].add_class(c) for i, c in enumerate(classes)]"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 180
+    },
+    {
+     "cell_type": "heading",
+     "level": 3,
+     "metadata": {},
+     "source": [
+      "ContainerWidgets"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "def create_label(cls):\n",
+      "    class_name = widgets.HTMLWidget(value=cls)\n",
+      "    container = widgets.ContainerWidget(children=[class_name])\n",
+      "    display(container)\n",
+      "    container.add_class(cls)\n",
       "\n",
-      "# Create each button and apply the style.  Also add margin to the buttons so they space\n",
-      "# themselves nicely.\n",
-      "for i in range(8):\n",
-      "    button = widgets.ButtonWidget(description=button_classes[i])\n",
-      "    button.set_css(\"margin\", \"5px\")\n",
-      "    display(button)\n",
-      "    if i > 0: # Don't add a class the first button.\n",
-      "        button.add_class(button_classes[i])\n",
-      "    "
+      "ret = [create_label(c) for c in [\n",
+      "    'alert', \n",
+      "    'alert alert-error', \n",
+      "    'alert alert-success', \n",
+      "    'alert alert-info'\n",
+      "]]"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 181
+    },
+    {
+     "cell_type": "heading",
+     "level": 3,
+     "metadata": {},
+     "source": [
+      "*ProgressWidgets"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "classes = [\n",
+      "    'progress-info', \n",
+      "    'progress-success', \n",
+      "    'progress-warning', \n",
+      "    'progress-danger',\n",
+      "    'progress-striped progress-info', \n",
+      "    'progress-striped progress-success', \n",
+      "    'progress-striped progress-warning', \n",
+      "    'progress-striped progress-danger',\n",
+      "    'active progress-striped progress-info', \n",
+      "    'active progress-striped progress-success', \n",
+      "    'active progress-striped progress-warning', \n",
+      "    'active progress-striped progress-danger',\n",
+      "]\n",
+      "ws = [widgets.IntProgressWidget(value=50, description=c) for c in classes]\n",
+      "ret = [display(w) for w in ws]\n",
+      "ret = [ws[i].add_class(c) for i, c in enumerate(classes)]"
      ],
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 8
+     "prompt_number": 182
+    },
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Visibility"
+     ]
     },
     {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "It is also useful to be able to remove CSS classes from widgets.\n",
-      "The `remove_class` method allows you to remove classes from widgets that have been displayed.\n",
-      "Like `add_class`, it must be called after the widget has been displayed."
+      "Sometimes it is necessary to hide or show widgets in place, without having to redisplay the widget.\n",
+      "The `visibility` property of widgets can be used to hide or show widgets that have already been displayed (as seen below)."
      ]
     },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "print(widgets.DOMWidget.remove_class.__doc__)"
+      "string = widgets.LatexWidget(value=\"Hello World!\")\n",
+      "display(string) "
      ],
      "language": "python",
      "metadata": {},
-     "outputs": [
-      {
-       "output_type": "stream",
-       "stream": "stdout",
-       "text": [
-        "Remove class[es] from a DOM element.\n",
-        "\n",
-        "        Parameters\n",
-        "        ----------\n",
-        "        class_names: unicode or list\n",
-        "            Class name(s) to remove from  the DOM element(s).\n",
-        "        selector: unicode (optional)\n",
-        "            JQuery selector to select the DOM element(s) that the class(es) will\n",
-        "            be removed from.\n",
-        "        \n"
-       ]
-      }
+     "outputs": [],
+     "prompt_number": 183
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "string.visible=False"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 184
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "string.visible=True"
      ],
-     "prompt_number": 9
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 185
     },
     {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "The example below animates an alert using different bootstrap styles."
+      "In the example below, a form is rendered, which conditionally displays widgets depending on the state of other widgets.  Try toggling the student checkbox."
      ]
     },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "import time\n",
-      "label = widgets.LatexWidget(value = \"$\\\\textbf{ALERT:} Hello World!$\")\n",
-      "display(label)\n",
+      "form = widgets.ContainerWidget()\n",
+      "first = widgets.TextWidget(description=\"First Name:\")\n",
+      "last = widgets.TextWidget(description=\"Last Name:\")\n",
+      "\n",
+      "student = widgets.CheckboxWidget(description=\"Student:\", value=False)\n",
+      "school_info = widgets.ContainerWidget(visible=False, children=[\n",
+      "    widgets.TextWidget(description=\"School:\"),\n",
+      "    widgets.IntTextWidget(description=\"Grade:\", min=0, max=12)\n",
+      "    ])\n",
       "\n",
-      "# Apply twitter bootstrap alert class to the label.\n",
-      "label.add_class(\"alert\")\n",
+      "pet = widgets.TextWidget(description=\"Pet's Name:\")\n",
+      "form.children = [first, last, student, school_info, pet]\n",
+      "display(form)\n",
       "\n",
-      "# Animate through additional bootstrap label styles 3 times\n",
-      "additional_alert_styles = ['alert-error', 'alert-info', 'alert-success']\n",
-      "for i in range(3 * len(additional_alert_styles)):\n",
-      "    label.add_class(additional_alert_styles[i % 3])\n",
-      "    label.remove_class(additional_alert_styles[(i-1) % 3])\n",
-      "    time.sleep(1)\n",
-      "        "
+      "def on_student_toggle(name, value):\n",
+      "    if value:\n",
+      "        school_info.visible = True\n",
+      "    else:\n",
+      "        school_info.visible = False\n",
+      "student.on_trait_change(on_student_toggle, 'value')\n"
      ],
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 10
+     "prompt_number": 186
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "[Next](Custom Widget - Hello World.ipynb)"
+     ]
     }
    ],
    "metadata": {}