Sets the comparison function used when sorting to be @sort_func. If the current sort column id of @sortable is the same as @sort_column_id, then the model will sort using this function.
the sort column id to set the function for
The comparison function
User data to pass to @sort_func, or %NULL
Destroy notifier of @user_data, or %NULL
See Implementation
Sets the comparison function used when sorting to be @sort_func. If the current sort column id of @sortable is the same as @sort_column_id, then the model will sort using this function.