Returns a list with all the class names defined for the widget at position pos in the hierarchy defined in path.
position to query, -1 for the path head
The list of classes, This is a list of strings, the GSList contents are owned by GTK+, but you should use g_slist_free() to free the list itself.
3.0
Returns a list with all the class names defined for the widget at position pos in the hierarchy defined in path.