I have this call to the theme function in my code :
print theme('image_style', array( 'path' => $news_image['uri'], 'style_name' => 'thumbnail', 'alt' => $news_image['alt'], 'title' => $news_image['title'],) );
However in the theme function documentation you can read :
Avoid calling this function directly. It is preferable to replace direct calls to the theme() function with calls to drupal_render() by passing a render array with a #theme key to drupal_render(), which in turn calls theme().
So, how do I rewrite the above simple function using drupal_render ?