on-close in frame:register-group-mixin
Called just before the window is closed (e.g., by the window manager).
This method is not called by
show .
See also
can-close?.
( -> voidsend a-frame:register-group-mixin on-close)
First calls the super method.
Next, calls the
remove-frame method of the result of
group:get-the-frame-group with this as an argument.
Finally, unless
exit:exiting? returns #t,
and if there are no more
frames open, it calls
exit:exit.