gnus-mime-security-button-menu

gnus-mime-security-button-menu is a variable defined in `gnus-art.el'.
Its value is

(keymap "Security Part"
	(Show\ Detail menu-item "Show Detail" gnus-article-press-button)
	(Save\.\.\. menu-item "Save..." gnus-mime-security-save-part)
	(Pipe\ To\ Command\.\.\. menu-item "Pipe To Command..." gnus-mime-security-pipe-part))

Documentation:
Security button menu.