bug#8911: bs-cycle-next deletes window in some cases.

[martin rudalics <rudalics@gmx.at>]

 > Let me also be clear that it is not about hook vs option.  It would be fine with
 > me if we had a user option for this instead of a hook, as long as it let you do
 > just as much.

Since I hardly ever bury a buffer please tell me when and how you want
to set up things and what precisely you want that option to do.  We now
have an option called `frame-auto-delete' which might be expanded to do
something in this sense.

 > E.g., a function to be invoked after the buffer order is changed.

`buffer-list-update-hook' is run when the "buffer order" changes.  Note
that there were "f + 1" buffer orders in Emacs 23 where "f" is the
number of live frames and there are "f + w + 1" buffer orders in Emacs
24 where "w" is the number of live windows.

 > Function
 > `ignore' would take care of the do-nothing case.  The function would need to
 > accept the buffer as its (first) argument.

`buffer-list-update-hook' doesn't have a buffer as argument.  We could
change that.  But this would not necessarily tell you enough about the
frame that should be deleted or iconified.

 > What I object to is Stefan's proposal of an option that allows only a choice
 > between deleting the frame and iconifying it.

martin