file-menu:new-callback in frame:standard-menus<%>
This method is called when the new menu-item of the file-menu menu is selected.
(-> voidsenda-frame:standard-menusfile-menu:new-callbackitemevt)
item: (instance (derived-frommenu-item%))
evt: (instancecontrol-event%)Defaultly bound to:
(λ (item control) (handler:edit-file #f) #t)