reapplied as soon as point moves away from the symbol. If
set to nil, the prettification persists even when point is
on the symbol."
+ :version "25.1"
:type '(choice (const :tag "Never unprettify" nil)
(const :tag "Unprettify when point is inside" t)
(const :tag "Unprettify when point is inside or at right edge" right-edge))