Because multiple clients may use the same style wordbreak object, some
mechanism is needed to know when an object should be
destroyed. Calling AdjustUsage with addUser = TRUE
increments the reference counter on the style list, so that it won't
be destroyed by another user. If addUser = FALSE, the reference
count is decremented. The object is not automatically destroyed
if the reference count goes to 0. An object should only be destroyed
when wxMediaWordbreakMap::IsUsed (section 
)
returns FALSE.