Queries the type of the state of action.
If the action is stateful (e.g. created with
g_simple_action_new_stateful()) then this function returns the
GVariantType of the state. This is the type of the initial value
given as the state. All calls to g_action_change_state() must give a
GVariant of this type and g_action_get_state() will return a
GVariant of the same type.
If the action is not stateful (e.g. created with g_simple_action_new())
then this function will return NULL. In that case, g_action_get_state()
will return NULL and you must not call g_action_change_state().
Since 2.28
Queries the type of the state of action. If the action is stateful (e.g. created with g_simple_action_new_stateful()) then this function returns the GVariantType of the state. This is the type of the initial value given as the state. All calls to g_action_change_state() must give a GVariant of this type and g_action_get_state() will return a GVariant of the same type. If the action is not stateful (e.g. created with g_simple_action_new()) then this function will return NULL. In that case, g_action_get_state() will return NULL and you must not call g_action_change_state(). Since 2.28