Some SLIME commands create temporary buffers to display their results. Although these buffers usually have their own special-purpose major-modes, certain conventions are observed throughout.
Temporary buffers can be dismissed by pressing q. This kills the
buffer and restores the window configuration as it was before the
buffer was displayed. Temporary buffers can also be killed with the
usual commands like kill-buffer, in which case the previous
window configuration won't be restored.
Pressing RET is supposed to “do the most obvious useful thing.” For instance, in an apropos buffer this prints a full description of the symbol at point, and in an XREF buffer it displays the source code for the reference at point. This convention is inherited from Emacs's own buffers for apropos listings, compilation results, etc.
Temporary buffers containing Lisp symbols use slime-mode in
addition to any special mode of their own. This makes the usual
SLIME commands available for describing symbols, looking up
function definitions, and so on.
Initial focus of those “description” buffers depends on the variable
slime-description-autofocus. If nil (the default),
description buffers do not receive focus automatically, and vice
versa.