Name
percent-visible -- Return the percent of WIN currently in the viewport as a real in [0,100].
Synopsis
(percent-visible #&optional (win (get-window)))
Description
Return the percent of WIN currently in the viewport as a real in [0,100].
Note that this does not consider other windows which may
obscure WIN; it only checks what fraction of WIN would be visible
if it were on top (unobscured).