Improvements in Drupal Gardens way: How do I place an input filter selector in CKEditor?
This is the code responsible for those modifications.

(function ($) {

Drupal.gardens_misc = Drupal.gardens_misc || {};

Drupal.behaviors.gardens_misc = {
  attach: function(context, settings) {
    if (typeof CKEDITOR != 'undefined') {
      // Bind events to handle enabling and disabling of the WYSIWYG.
      CKEDITOR.on('instanceReady', Drupal.behaviors.gardens_misc.instanceLoaded);
    }

    $('.wysiwyg', context).closest('.text-format-wrapper').once('wysiwyg-tabs', function() {
      var $tabs = $('&lt;div class="wysiwyg-tab-wrapper"&gt;&lt;/div&gt;').insertBefore($(this).find('.form-textarea-wrapper'));
      $('&lt;div class="wysiwyg-tab enable first"&gt;' + Drupal.t('WYSIWYG') + '&lt;/div&gt;')
        .bind('click', this, Drupal.behaviors.gardens_misc.tabToggle)
        .appendTo($tabs);
      $('&lt;div class="wysiwyg-tab disable last"&gt;' + Drupal.t('HTML') + '&lt;/div&gt;')
        .bind('click', this, Drupal.behaviors.gardens_misc.tabToggle)
        .appendTo($tabs);
    });
  },
  instanceLoaded: function(event) {
    var $wrapper = $(event.editor.container.$).closest('.text-format-wrapper');
    var $original = $wrapper.find('.wysiwyg');
    var $clone = $original.clone().val($original.val());
    $clone.bind('change', function(event) {
      $original.val($clone.val()).change();
    });
    $wrapper.find('.cke_toolbox').removeAttr('onmousedown').prepend($clone);
    $wrapper.find('.wysiwyg-tab.enable').addClass('wysiwyg-active');
    $wrapper.find('.wysiwyg-tab.disable').removeClass('wysiwyg-active');
  },
  tabToggle: function (event) {
    if (!$(this).hasClass('wysiwyg-active')) {
      $(this).closest('.text-format-wrapper').find('.wysiwyg-toggle-wrapper a').click();
    }
  }
};

/**
 * Overides the default attach behavior for text formats without an editor
 */
Drupal.wysiwyg.editor.attach.none = function(context, params, settings) {
  var $field = $('#' + params.field);
  var $original = $('#' + params.trigger);
  var $clone = $original.clone().val($original.val());
  var $container = $('&lt;div class="wysiwyg-none-header"&gt;&lt;/div&gt;');
  $container.append($clone).insertBefore($field);
  $clone.bind('change', function(event) {
    $original.val($clone.val()).change();
  });

  // @todo: Need to display the allowed tags here
  var tags = Drupal.settings.wysiwyg_formats[$original.val()];
  $('&lt;span&gt;&lt;b&gt;' + Drupal.t('Allowed tags: ') + '&lt;/b&gt;' + tags + '&lt;/span&gt;').appendTo($container);


  // Original behavior
  if (params.resizable) {
    var $wrapper = $field.closest('.form-textarea-wrapper');
    $wrapper.addClass('resizable');
    if (Drupal.behaviors.textarea.attach) {
      Drupal.behaviors.textarea.attach();
    }
  }

  $field.closest('.text-format-wrapper').find('.wysiwyg-tab.enable').removeClass('wysiwyg-active');
  $field.closest('.text-format-wrapper').find('.wysiwyg-tab.disable').addClass('wysiwyg-active');
};

/**
 * Overides the default detach behavior for text formats without an editor
 */
Drupal.wysiwyg.editor.detach.none = function(context, params) {
  $('#' + params.field).siblings('.wysiwyg-none-header').remove();

  // Original behavior
  if (typeof params != 'undefined') {
    var $wrapper = $('#' + params.field).parents('.form-textarea-wrapper:first');
    $wrapper.removeOnce('textarea').removeClass('.resizable-textarea')
      .find('.grippie').remove();
  }
};

})(jQuery);;


Save the above in its own file e.g. drupalgardens_wysiwyg.js, then either add the script to the .info file of your theme/module or add the file on the relevant page(s) using drupal_add_js or via the #attached property of a form/render array.

To get this to work on a non-DrupalGardens site, I had to comment out the two lines below the @todo comment around line 53. You may need to further tweak the code depending on how you have your wysiwyg profiles configured.