WordPress at a glance
action is not described

install_themes_table_header action-hook . WP 2.8.0

Fires in the Install Themes list table header.

Usage

add_action( 'install_themes_table_header', 'action_function_name_2086' );
function action_function_name_2086(){
	// action...
}

Where the hook is called

WP_Theme_Install_List_Table::display()
install_themes_table_header
wp-admin/includes/class-wp-theme-install-list-table.php 194
do_action( 'install_themes_table_header' );

Where the hook is used (in WP core)

wp-admin/includes/class-wp-theme-install-list-table.php 111
add_action( 'install_themes_table_header', 'install_theme_search_form', 10, 0 );