Calling completion-show-tooltip when completing, bound to S-Down when completion-use-tooltip is enabled, displays a list of available completions in a tooltip. The completion-tooltip-cycle and completion-tooltip-cycle-backwards commands, bound to the down and up arrow keys, can then be used to select a completion from the list. The following variables affect the completion tooltip: The tooltip can also be displayed automatically when completing, optionally after a time-delay. See Auto-Show a List of Completions.
:foreground
,
:background
and :family
attributes are actually used.