Some buffers are shown in windows for perusal rather than for editing. Help commands (Help) typically use a buffer called *Help* for that purpose, minibuffer completion (Completion) uses a buffer called *Completions*, etc. Such buffers are usually displayed only for a short period of time. Normally, Emacs chooses the window for such temporary displays via display-buffer, as described in the previous subsection. The *Completions* buffer, on the other hand, is normally displayed in a window at the bottom of the selected frame, regardless of the number of windows already shown on that frame. If you prefer Emacs to display a temporary buffer in a different fashion, customize the variable display-buffer-alist (Choosing a Window for Displaying a Buffer) appropriately. For example, to display *Completions* always below the selected window, use the following form in your initialization file (Init File):

@group
(setopt
 display-buffer-alist
 '(("\\*Completions\\*" display-buffer-below-selected)))
@end group

The *Completions* buffer is also special in the sense that Emacs usually tries to make its window just as large as necessary to display all of its contents. To resize windows showing other temporary displays, like, for example, the *Help* buffer, turn on the minor mode (Minor Modes) temp-buffer-resize-mode (Temporary Displays). The maximum size of windows resized by temp-buffer-resize-mode can be controlled by customizing the options temp-buffer-max-height and temp-buffer-max-width (Temporary Displays), and cannot exceed the size of the containing frame.