bug#24293: 25.1; Display bug: icomplete prompt not visible with icomplete-separator "\n"

[Drew Adams]

> Maybe we can fix it in icomplete instead.  AFAIK icomplete tries to
> limit the number of shown candidates according to some settings like
> maximum number of lines to display, but doesn't handle the case of a
> separator including a newline character correctly.
> 
> Is it possible to determine reliably the number of lines a minibuffer
> window can display maximally for given max-mini-window-height?

1. Please take care not to break the case of a standalone minibuffer
frame, or any other context where the minibuffer can be resized to
accommodate a large number of icomplete candidates.

IOW, a newline separator is not a problem at all in some contexts.
Please don't limit or break that behavior.  Thx.

2. It's not clear to me why this should be handled in icomplete.el.
Doesn't the same problem arise if multi-line text is inserted in
the minibuffer or if any other program does something similar to
what icomplete does?  IOW, isn't it a general problem, which would
call for a general solution?