bug#34749: 26.1; `delete-windows-on': (1) doc, (2) bug, (3) bug, (4) candidates

[Drew Adams]

>  > I think we should simply try letting the user provide all possible
>  > values of the FRAME argument in interactive invocations, by using
>  > different forms of 'C-u'.
> 
> I have no idea how to do that.  And when trying to read the
> documentation on 'interactive' I nowhere detected where the "\nP"
> convention is described (which apparently turns a function's last (?)
> argument into the prefix argument).  Can someone enlighten me?

Are you asking what "\nP" means/does?  If so, the "\n" separates
arguments and the "P" stands for `current-prefix-arg', i.e., the
raw prefix argument.  This is pretty well documented in (elisp)
`Using Interactive' and (elisp) `Interactive Codes'.

  a string; its contents are a sequence of elements
  separated by newlines, one for each argument(1).  Each element
  consists of a code character (*note Interactive Codes::) optionally
  followed by a prompt (which some code characters use and some
  ignore).  Here is an example:

       (interactive "P\nbFrobnicate buffer: ")

  The code letter ‘P’ sets the command’s first argument to the raw
  command prefix (*note Prefix Command Arguments::).