Here are some things to change in the code
smileys.module
@124 >> When dialog is not chosen then let's not call the ui.dialog, this speeds things up a bit.

    $dialog = variable_get('smileys_enable_dialog', FALSE);

@141 >> Just as with the ui.dragable, let's check if there's no jquery_ui module if so let's use that.

if ($dialog) {
  $jquery_ui ? jquery_ui_add('ui.dialog') : drupal_add_js($path . '/scripts/ui.core.dialog.js');
  //if the jquery_ui module is present then we call that stylesheet
  if($jquery_ui){
    drupal_add_css($path = drupal_get_path('module', 'jquery_ui') .'/jquery.ui/themes/default/ui.all.css', $type = 'module', $media = 'all', $preprocess = TRUE);
  }
}

smileys.css
@153 >> background:; is not valid so we have to give it the none value. I know ui.all.css has this bug also but let's fix it where we can.

  background:none;