A “typeout frame” is a special Emacs frame which is used instead of the echo area (minibuffer) to display messages from SLIME commands. This is an optional feature. The advantage of a typeout frame over the echo area is that it can hold more text, it can be scrolled, and its contents don’t disappear when you press a key. All potentially long messages are sent to the typeout frame, such as argument lists, macro expansions, and so on.
Ensure that a typeout frame exists, creating one if necessary.
If the typeout frame is closed then the echo area will be used again as usual.
To have a typeout frame created automatically at startup you should
slime-typeout-frame package. (see Loading Contribs.)
slime-typeout-frame-properties specifies the
height and possibly other properties of the frame. Its value is
make-frame. (See (elisp)Creating Frames.)