anchor.diff:  
   const String _raisedText =
     "# Raised buttons\n"
  -  "Raised buttons add dimension to mostly flat layouts. They emphasize"
  +  "Raised buttons add dimension to mostly flat layouts. They emphasize "
     "functions on busy or wide spaces.";
   
   const String _raisedCode =
  -"""// Create a flat button
  +"""// Create a raised button.
   new RaisedButton(
     child: new Text('BUTTON TITLE'),
     onPressed: () {
  
positive.code:   }
  );
  
  // Create a disabled button
  // The button is disabled because there is no
  // onPressed method specified
  new RaisedButton(
    child: new Text('BUTTON TITLE')
  );""";
  
  const String _flatText =
    "# Flat buttons\n"
    "A flat button is made of ink that displays ink reactions on press "
    "but does not lift. Use flat buttons on toolbars, in dialogs and "
    "inline with padding";
  
  const String _flatCode =
  """// Create a flat button
  new FlatButton(
    child: new Text('BUTTON TITLE'),
    onPressed: () {
  
negative.code:   "arrow.";
  
  const String _dropdownCode =
  """// Member variable holding value.
  String dropdownValue
  
  // Drop down button with string values.
  new DropDownButton<String>(
    value: dropdownValue,
    onChanged: (String newValue) {
      // null indicates the user didn't select a
      // new value.
      setState(() {
        if (newValue != null)
          dropdownValue = newValue;
  