Queries the type of the parameter that must be given when activating @action.
When activating the action using g_action_activate(), the #GVariant given to that function must be of the type returned by this function.
In the case that this function returns %NULL, you must not give any #GVariant, but %NULL instead.
Return: the parameter type
2.28
See Implementation
Queries the type of the parameter that must be given when activating @action.
When activating the action using g_action_activate(), the #GVariant given to that function must be of the type returned by this function.
In the case that this function returns %NULL, you must not give any #GVariant, but %NULL instead.
Return: the parameter type