Variable: minibuffer-scroll-window
minibuffer-scroll-window is a variable defined in window.c.
Value
nil
Documentation
Non-nil means it is the window that C-M-v in minibuffer should scroll.
Probably introduced at or before Emacs version 18.
Source Code
// Defined in /usr/src/emacs/src/window.c
DEFVAR_LISP ("minibuffer-scroll-window", Vminibuf_scroll_window,
doc: /* Non-nil means it is the window that C-M-v in minibuffer should scroll. */);