function add_comment()
{
   var stop = 0;
   if ( ! comment_form.name.value )
   {
      comment_form.name.className =  'input_alert';
      stop=1;
   }
   if ( ! comment_form.comment_text.value )
   {
      comment_form.comment_text.className =  'input_alert';
      stop=1;
   }
   
   if (stop)
   {
      form_alert_msg( 'Не заполнены необходимые поля' );
   }
   else
   {
      comment_form.name.className  =  'input_active';
      comment_form.comment_text.className =  'input_active';
      comment_form.submit();
   }
}