the data to insert
the #GCompareDataFunc used to compare elements in the queue. It is called with two elements of the @queue and @user_data. It should return 0 if the elements are equal, a negative value if the first element comes before the second, and a positive value if the second element comes before the first.
user data passed to @func
2.4
Inserts @data into @queue using @func to determine the new position.