file-menu:quit-callback in frame:standard-menus<%>
This method is called when the quit menu-item of the file-menu menu is selected.
(-> voidsenda-frame:standard-menusfile-menu:quit-callbackitemevt)
item: (instance (derived-frommenu-item%))
evt: (instancecontrol-event%)Defaultly bound to:
(λ (item control) (when (exit:user-oks-exit) (exit:exit)))