temp-buffer-resize-mode
temp-buffer-resize-mode is an interactive compiled Lisp function in `help.el
'.
(temp-buffer-resize-mode &optional ARG)
Toggle auto-resizing temporary buffer windows (Temp Buffer Resize Mode).
With a prefix argument ARG, enable Temp Buffer Resize mode if ARG
is positive, and disable it otherwise. If called from Lisp,
enable the mode if ARG is omitted or nil.
When Temp Buffer Resize mode is enabled, the windows in which we
show a temporary buffer are automatically resized in height to
fit the buffer's contents, but never more than
`temp-buffer-max-height' nor less than `window-min-height'.
A window is resized only if it has been specially created for the
buffer. Windows that have shown another buffer before are not
resized. A frame is resized only if `fit-frame-to-buffer' is
non-nil.
This mode is used by `help', `apropos' and `completion' buffers,
and some others.