Wordpress Tabbed Theme Options

<?php
/*
## To add a new tab:
      register a new setting using register_setting and create a validation function for the setting below
      Add a new add_settings_section with $id ( first param ) corresponding to the regsister_setting $option_group ( first parm)
      add a new key value set to the $tabs array in mytheme_admin_tabs()
      add blank callback functions for the add_settings_section - this must exist but will not actually display
      ... to add intro text etc add a mew section to tab_intro_text() (sections within tabs seemingly not possible)
## To add a new field:
      Add new add_settings_field and add it's callback function
*/

if ( is_admin() ) :
  include 'theme-options-functions.php';
  include 'theme-options-callbacks.php';

  // Create the tabs and fields
  function do_settings() {
    // -- general
    register_setting( 'general', 'general', 'general_validate' );
    add_settings_section('general', 'General', 'general_function', 'theme_options');
    add_settings_field('general1', 'General 1', 'general1', 'theme_options', 'general');
    add_settings_field('general2', 'General 2', 'general2', 'theme_options', 'general');
    // -- advanced
    register_setting( 'advanced', 'advanced', 'advanced_validate' );
    add_settings_section('advanced', 'Advanced', 'advanced_function', 'theme_options');
    add_settings_field('advanced1', 'Advanced 1', 'advanced1', 'theme_options', 'advanced');
  }

  // Create the options page
  function theme_options() {
    add_theme_page( 'Theme Options', 'Theme Options', 'edit_theme_options', 'theme_options', 'theme_options_page' );
  }

  // Admin Css
    function my_admin_head() {
    $url = get_bloginfo('stylesheet_directory') . '/adminstyle.css';  /* this would normally be 'template_directory' */
    echo "<link rel='stylesheet' href='$url' />\n";
  }

  // Actions
  add_action( 'admin_menu', 'theme_options' );
  add_action( 'admin_init', 'do_settings' );
  add_action('admin_head', 'my_admin_head');


  // Validation Functions
  // -- general
  function general_validate( $input ) {

    return $input;
  }

  // -- advanced
  function advanced_validate( $input ) {

    return $input;
  }



  // Callback functions
  // -- general tab add_settings_field functions
  function general1(){
   $options = get_option('general');
   echo "<p><input size='100' name='general[general1]' type='text' value='{$options['general1']}' /></p>";
  }
  function general2(){
   $options = get_option('general');
   echo "<p><input size='100' name='general[general2]' type='text' value='{$options['general2']}' /></p>";
  }



  // -- advanced tab add_settings_field functions
  function advanced1(){
   $options = get_option('advanced');
   echo "<p><input size='100' name='advanced[advanced1]' type='text' value='{$options['advanced1']}' /></p>";
  }


  // Blank settings_section functions - these must exist but cant be used anywhere under the current design
  function general_function(){
  }
  function advanced_function(){
  }


  // Generate options page
  function theme_options_page() {
    global $pagenow;
    if ( $pagenow == 'themes.php' && $_GET['page'] == 'theme_options' ) :
      if ( isset ( $_GET['tab'] ) ) :
          $tab = $_GET['tab'];
      else:
          $tab = 'general';
      endif;
    mytheme_admin_tabs($tab);
    options_tab_content($tab);
    endif;
  }

  // Generate tabs
  function mytheme_admin_tabs( $current = 'general' ) {
    $tabs = array( 'general' => 'General', 'advanced' => 'Advanced');
    $links = array();
    foreach( $tabs as $tab => $name ) :
      if ( $tab == $current ) :
          $links[] = "<a class='nav-tab nav-tab-active' href='?page=theme_options&tab=$tab'>$name</a>";
      else :
          $links[] = "<a class='nav-tab' href='?page=theme_options&tab=$tab'>$name</a>";
      endif;
    endforeach;
    echo '<h2>';
    foreach ( $links as $link )
      echo $link;
    echo '</h2>';
  }

  // Generate tab content
  function options_tab_content($setting) {
    if ( ! isset( $_REQUEST['settings-updated'] ) )
      $_REQUEST['settings-updated'] = false; ?>
    <div class="wrap">
    <?php screen_icon(); echo "<h2>" . get_current_theme() . __( ' Theme Options' ) . "</h2>"; ?>
    <?php if ( false !== $_REQUEST['settings-updated'] ) : ?>
    <div class="updated fade"><p><strong><?php _e( 'Options saved', 'sampletheme' ); ?></strong></p></div>
    <?php endif; ?>
      <form method="post" action="options.php">
        <?php settings_fields($setting); ?>
        <?php tab_intro_text($setting); ?>
        <?php do_settings_fields( 'theme_options', $setting ) ?>
        <p class="submit"><input type="submit" class="button-primary" value="Save Options" /></p>
      </form>
    </div>
    <?php
  }

  // Generate intro/description text for tabs
  function tab_intro_text($tab){
    echo '<div class = "tab_intro_text">';
    switch ( $tab ) :
    case 'general' :
    echo "This is the general tab";
    break;
    case 'advanced' :
    echo "This is the advanced tab";
    break;
    endswitch;
    echo '</div>';
  }


endif;
?>