Fix widget dropdown example

Thanks to @parente in  #7350 for spotting this.

examples/Interactive Widgets/Widget List.ipynb

@@ -1,580 +1,586 b''
 {
  "cells": [
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "[Index](Index.ipynb) - [Back](Widget Basics.ipynb) - [Next](Widget Events.ipynb)"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "# Widget List"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "## Complete list"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "For a complete list of the widgets available to you, you can list the classes in the widget namespace (as seen below).  `Widget` and `DOMWidget`, not listed below, are base classes."
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "from IPython.html import widgets\n",
     "[n for n in dir(widgets) if not n.endswith('Widget') and n[0] == n[0].upper() and not n[0] == '_']"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "## Numeric widgets"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "There are 8 widgets distributed with IPython that are designed to display numeric values.  Widgets exist for displaying integers and floats, both bounded and unbounded.  The integer widgets share a similar naming scheme to their floating point counterparts.  By replacing `Float` with `Int` in the widget name, you can find the Integer equivalent."
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "### FloatSlider"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.FloatSlider(\n",
     "    value=7.5,\n",
     "    min=5.0,\n",
     "    max=10.0,\n",
     "    step=0.1,\n",
     "    description='Test:',\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "Sliders can also be **displayed vertically**."
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.FloatSlider(\n",
     "    value=7.5,\n",
     "    min=5.0,\n",
     "    max=10.0,\n",
     "    step=0.1,\n",
     "    description='Test',\n",
     "    orientation='vertical',\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "### FloatProgress"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.FloatProgress(\n",
     "    value=7.5,\n",
     "    min=5.0,\n",
     "    max=10.0,\n",
     "    step=0.1,\n",
     "    description='Loading:',\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "### BoundedFloatText"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.BoundedFloatText(\n",
     "    value=7.5,\n",
     "    min=5.0,\n",
     "    max=10.0,\n",
     "    description='Text:',\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "### FloatText"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.FloatText(\n",
     "    value=7.5,\n",
     "    description='Any:',\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "## Boolean widgets"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "There are two widgets that are designed to display a boolean value."
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "### ToggleButton"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.ToggleButton(\n",
     "    description='Click me',\n",
     "    value=False,\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "### Checkbox"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.Checkbox(\n",
     "    description='Check me',\n",
     "    value=True,\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "## Selection widgets"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "There are four widgets that can be used to display single selection lists.  All four inherit from the same base class.  You can specify the **enumeration of selectables by passing a list**.  You can **also specify the enumeration as a dictionary**, in which case the **keys will be used as the item displayed** in the list and the corresponding **value will be returned** when an item is selected."
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "### Dropdown"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "from IPython.display import display\n",
     "w = widgets.Dropdown(\n",
-    "    values=[1, 2, 3],\n",
-    "    value=2,\n",
+    "    values=['1', '2', '3'],\n",
+    "    value='2',\n",
     "    description='Number:',\n",
     ")\n",
     "display(w)"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "w.value"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "The following is also valid:"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "w = widgets.Dropdown(\n",
     "    values={'One': 1, 'Two': 2, 'Three': 3},\n",
     "    value=2,\n",
     "    description='Number:',\n",
     ")\n",
     "display(w)"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "w.value"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "### RadioButtons"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.RadioButtons(\n",
     "    description='Pizza topping:',\n",
     "    values=['pepperoni', 'pineapple', 'anchovies'],\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "### Select"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.Select(\n",
     "    description='OS:',\n",
     "    values=['Linux', 'Windows', 'OSX'],\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "### ToggleButtons"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.ToggleButtons(\n",
     "    description='Speed:',\n",
     "    values=['Slow', 'Regular', 'Fast'],\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "## String widgets"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "There are 4 widgets that can be used to display a string value.  Of those, the **`Text` and `Textarea` widgets accept input**.  The **`Latex` and `HTML` widgets display the string** as either Latex or HTML respectively, but **do not accept input**."
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "### Text"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.Text(\n",
     "    description='String:',\n",
     "    value='Hello World',\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "### Textarea"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.Textarea(\n",
     "    description='String:',\n",
     "    value='Hello World',\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "### Latex"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.Latex(\n",
     "    value=\"$$\\\\frac{n!}{k!(n-k)!} = \\\\binom{n}{k}$$\",\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "### HTML"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.HTML(\n",
     "    value=\"Hello <b>World</b>\"\n",
     ")"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "slide"
     }
    },
    "source": [
     "## Button"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": false
    },
    "outputs": [],
    "source": [
     "widgets.Button(description='Click me')"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
     "[Index](Index.ipynb) - [Back](Widget Basics.ipynb) - [Next](Widget Events.ipynb)"
    ]
   }
  ],
  "metadata": {
   "kernelspec": {
-   "codemirror_mode": {
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-  "signature": "sha256:83b39d018a7a6ae0a324b9f3d38debafbfb2ed0a114e4bbd357fb318f8f23438"
+  "language_info": {
+   "codemirror_mode": {
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