This sets an opaque, named pointer on an object.
The name is specified through a GQuark (retrived e.g. via
g_quark_from_static_string()), and the pointer
can be gotten back from the object with g_object_get_qdata()
until the object is finalized.
Setting a previously set user data pointer, overrides (frees)
the old pointer set, using NULL as pointer essentially
removes the data stored.
This sets an opaque, named pointer on an object. The name is specified through a GQuark (retrived e.g. via g_quark_from_static_string()), and the pointer can be gotten back from the object with g_object_get_qdata() until the object is finalized. Setting a previously set user data pointer, overrides (frees) the old pointer set, using NULL as pointer essentially removes the data stored.