file-menu:close-callback in frame:standard-menus<%>
This method is called when the close menu-item of the file-menu menu is selected.
( -> void
send a-frame:standard-menus file-menu:close-callback item evt)
item : (instance (derived-from menu-item%))
evt : (instance control-event%)
Defaultly bound to:
(lambda (item control) (when (can-close?) (on-close) (show #f)) #t)