The type of the function that is used to convert from a value stored
in a #GSettings to a value that is useful to the application.
If the value is successfully mapped, the result should be stored at
result and %TRUE returned. If mapping fails (for example, if value
is not in the right format) then %FALSE should be returned.
If value is %NULL then it means that the mapping function is being
given a "last chance" to successfully return a valid value. %TRUE
must be returned in this case.
The type of the function that is used to convert from a value stored in a #GSettings to a value that is useful to the application.
If the value is successfully mapped, the result should be stored at
resultand %TRUE returned. If mapping fails (for example, ifvalueis not in the right format) then %FALSE should be returned.If
valueis %NULL then it means that the mapping function is being given a "last chance" to successfully return a valid value. %TRUE must be returned in this case.