A modal completion dialog automatically has a filter if the number of possible completions exceeds the value of the option Works > Tools > Preferences... > Environment > General > Add a filter to dialog lists longer than: . By default this option has value 25.
The filter options described above are also available in a modal completion dialog, and are controlled by the same keyboard gestures, for example
. See Advanced Filtering for details.
LispWorks IDE User Guide (Unix version) - 25 Nov 2011