NULL is OK, both for passing and for returning.

Parameter points to an array of items.

This parameter is a 'user_data', for callbacks; many bindings can pass NULL here.

Generics and defining elements of containers and arrays.

NULL may be passed as the value in, out, in-out; or as a return value.

Out parameter, where caller must allocate storage.

Out parameter, where caller must allocate storage.

The callback is valid until first called.

The callback is valid only during the call to the method.

The callback is valid until the GDestroyNotify argument is called.

The intention of a Stable interface is to enable arbitrary third parties to develop applications to these interfaces, release them, and have confidence that they will run on all minor releases of the product (after the one in which the interface was introduced, and within the same major release). Even at a major release, incompatible changes are expected to be rare, and to have strong justifications.

Free data container after the code is done.

Free data after the code is done.

Don't free data after the code is done.