Read the sources if you really want to know something that
(a) is undocumented, so may not be the same across all releases
(b) is undocumented, so may not be the same across all Look&Feels
(c) is undocumented, so will almost certainly come back to bite you in the butt when you least expect it.
Do you really need some custom behavior to apply when the user clicks the mouse to make a selection, and normal, decustomised behavior when the selection is made using the keyboard?
What custom behavior?
There are no new questions, but there may be new answers.