tooltip-mode

tooltip-mode is an interactive compiled Lisp function in `tooltip.el'.

It is bound to <menu-bar> <options> <showhide> <showhide-tooltip-mode>.

(tooltip-mode &optional ARG)

Toggle Tooltip mode.
With a prefix argument ARG, enable Tooltip mode if ARG is positive,
and disable it otherwise. If called from Lisp, enable the mode
if ARG is omitted or nil.

When this global minor mode is enabled, Emacs displays help
text (e.g. for buttons and menu items that you put the mouse on)
in a pop-up window.

When Tooltip mode is disabled, Emacs displays help text in the
echo area, instead of making a pop-up window.