Variable: text-property-default-nonsticky

Alist of properties vs the corresponding non-stickiness.
Each element has the form (PROPERTY . NONSTICKINESS).

If a character in a buffer has PROPERTY, new text inserted adjacent to
the character doesn't inherit PROPERTY if NONSTICKINESS is non-nil,
inherits it if NONSTICKINESS is nil. The `front-sticky' and
`rear-nonsticky' properties of the character override NONSTICKINESS.