very messy! (need to take out inline javascript and refactor)

init.rb

require 'tabset_helpers.rb'

ActionView::Base.send(:include, TabsetHelpers)

tabset_helpers.rb

module TabsetHelpers
  def tabset(options={}, &block)
    # set a default id
    options[:id] ||= "tabset_div_" + (  $tabset_unique_id = ($tabset_unique_id||0) + 1 ).to_s
    id = options[:id]
    selected_tab = options.delete(:selected) || "" if options.has_key?(:selected)
    @tabset_tabs=[]
    tabs_content = capture(&block)
    tabs_html = ""
    
    # output the tabs
    @tabset_tabs.each { | tab |
      tabs_html << "<li id='#{tab[:id]}_tab_button'><a href=\"javascript:$('#{id}').tabset.gotab('#{tab[:id]}');\"><span>#{tab[:label]}</span></a></li>"
    }
    
    tabs_html = content_tag(
      :div, 
      content_tag(:ul, tabs_html),
      options
    )
        
    tab_names = @tabset_tabs.map{ |tab| tab[:id] }
    
    # output the javascript
    js_output = <<END_OF_STRING
      Tabset = Class.create();
      Tabset.prototype = {
        initialize: function(tabbar_container_id, tab_names)
        {
          this.tab_elements=$H();
          this.tabbar_container = $(tabbar_container_id); 
          this.tabbar_container.tabset = this;
          this.master_parent = null;
          this.tab_content_container = this.tabbar_container.next("div");
          
          // put tabs somewhere so they and their content can still be found with selectors
          this.tab_content_storage = new Element("div", {style: "display: none; position: absolute;"});
           
          this.tab_content_container.up().appendChild(this.tab_content_storage);
          $A(tab_names).each(function(tab) {
            tab_element = this.tab_content_container.down('#' + tab + '_tab');
            this.tab_elements.set(tab, tab_element);
            this.master_parent = tab_element.parentNode;
          }.bind(this));
        },
        gotab: function(tab_name)
        {
          if (! this.tab_elements.get(tab_name)) return false;
          
          $A(this.master_parent.childNodes).each(function(node) { 
            this.master_parent.removeChild(node);
            if(node.tagName == "DIV") {
              this.tab_content_storage.appendChild(node);
            }
          }.bind(this));
          (selected_tab = this.tabbar_container.down(".current")) && selected_tab.removeClassName("current");
          this.tabbar_container.down("#" + tab_name + '_tab_button').addClassName("current");
          
          node = this.tab_elements.get(tab_name);
          node.remove();
          this.master_parent.appendChild(node);
        }
      }
    
    new Tabset("#{id}", #{tab_names.to_json});
    
END_OF_STRING
    
    selected_tab||= @tabset_tabs.first[:id]
    js_output << "$('#{id}').tabset.gotab('#{selected_tab}');"

    concat(tabs_html, block.binding)
    concat("<div>", block.binding)
    concat(tabs_content, block.binding)
    concat("</div>", block.binding)
    
    # Output all of the necessary javascript
    concat("<script language='javascript'>#{js_output}</script>", block.binding)
  end
  
  def define_tab(id, label, &block)
    @tabset_tabs << {
      :id => id,
      :label => label
    }
    
    concat("<div id='#{id}_tab'>", block.binding)
    concat(capture(&block), block.binding)
    concat("</div>", block.binding)
  end

end