Turns on the mouse on character-based systems. (By default the mouse is invisible.) The value of RETURN-CODE is set to 1 if a mouse is present, 0 if no mouse is found. (Takes no additional parameters.)
On some machines there is an appreciable delay when the mouse is enabled.
Under graphical environments such as Windows, ENABLE-MOUSE is not necessary. It sets the value of RETURN-CODE properly, but no other action occurs, because the mouse is always enabled in these environments.