The LispWorks Editor uses this functionality to display the special window near the cursor position, which is called in-place completion.
Tools in the LispWorks IDE that ask for a named object (for example, the Class Browser and the Generic Function Browser) in a text input pane have in-place completion which is invoked by the
Up
and
Down
keys.
Set the Preferences... Environment > General > Use in-place completion option to use in-place completion.