WordPress at a glance
filter is not described

gallery_style filter-hook . WP 2.5.0

Filters the default gallery shortcode CSS styles.

Usage

add_filter( 'gallery_style', 'filter_function_name_7128' );
function filter_function_name_7128( $gallery_style ){
	// filter...

	return $gallery_style;
}
$gallery_style(string)
Default CSS styles and opening HTML div container for the gallery shortcode output.

Where the hook is called

In file: /wp-includes/media.php
gallery_style
wp-includes/media.php 1771
$output = apply_filters( 'gallery_style', $gallery_style . $gallery_div );

Where the hook is used (in WP core)

Does not used.