upload_ui_over_quota action-hook . WP 3.5.0

Fires when an upload will exceed the defined upload space quota for a network site.

Usage

add_action( 'upload_ui_over_quota', 'action_function_name_4766' );
function action_function_name_4766(){
	// action...
}

Where the hook is called

do_action( 'upload_ui_over_quota' );

do_action( 'upload_ui_over_quota' );

Where the hook is used (in WP core)

add_action( 'upload_ui_over_quota', 'multisite_over_quota_message' );