EXTJS With Rails.. render partials into divs

Ok so I have been playing with extjs and rails for about a week and I
feel I have made good progress. But I have gotten stuck. I have an
extjs form that has a button that submits data to my login method. I
want to have the controller update just a div in my page without
reloading or redirecting the page. This works great if I use just an
normal ruby on rails link_to. However, when I use a extjs button and
set the handler to call the controller the controller cannot render a
partial. It just hangs.

So here is my exmple. I have a very simple forum:

[CODE] var simple = new Ext.FormPanel({
        labelWidth: 75, // label settings here cascade unless
        title: 'Sign In',
        bodyStyle:'padding:5px 5px 0',
        width: 350,
        defaults: {width: 230},
        defaultType: 'textfield',

        items: [{
                fieldLabel: 'Screen Name',
                name: 'screen_name',
              fieldLabel: 'Password',
              name: 'password'

        buttons: [{
            text: 'Login',
            type: 'submit',
            handler: function(){
            simple.form.submit({url: '/users/login?format_ext_json',
waitMsg: 'Authenticating..'});}
            text: 'Cancel'


Then I have a users controller and inside that controller I have a

def login
    @title = "Log in to pinktomato"
      if request.get?
        @user = User.new(:remember_me => remember_me_string)
      elsif param_posted?(:screen_name)
        @user = User.new()
        @user.screen_name = params[:screen_name]
        @user.password = params[:password]
        user = User.find_by_screen_name_and_password
        if user
          logger.info("found user")
          @user.remember_me? ? user.remember!(cookies) : user.forget!
          flash[:notice] = "User #{user.screen_name} logged in!"
          render :text => "I HOPE THIS SHOWS"

          # Don't show the password in the view
          flash[:notice] = "Invalid screen name/password combination"
  end[/CODE]The "render :text" never renders.. It actually just hangs
on the authenticating when u click the login button. What I am
assuming is that possibly the controller has lost reference to the div
it should update. Is this possile. Since when I use a regular link_to
command in rails the login method works fine. Only when called from
the extjs form.

I have tried lost of stuff so far even

[CODE] respond_to do |format|
          format.ext_json { render(:update) {|page| page.replace_html
"home" ,:partial=>"loggedIn") } }


I hope my problem makes sense. I cannot find reference to this
anywhere. I downloaded the extjs scaffold and I took at look at the
generated code because it does create a create method for the
scaffold. However this pre generated scaffold just redirects the user.
I don't want the page to referesh. Is this my only choice?

[CODE] def create
    @site = Site.new(params[:site])

    respond_to do |format|
      if @site.save
        flash[:notice] = 'Site was successfully created.'
        format.ext_json { render(:update) {|page| page.redirect_to
sites_path } }
        format.ext_json { render :json => @site.to_ext_json(:success
=> false) }
  end[/CODE]Please any help would be appreciated..


I am getting a little further if I use

          respond_to do |format|
            format.ext_json { render(:update) {|page|
page.replace_html "home", :partial => "loggedIn"} }

The partial loads, however the waiting message from the forum never
goes away.
It just hangs..