use of 'private' in C++ classes makes it very difficult to create a derived class that's capable of providing functionality that extends the original, without actually cloning the code yourself to 'make it work anyway'. In my view, 'private' is an outdated and short-sighted concept anyway, particularly with open source. Using 'protected' accomplishes the same thing without tying anyone's hands. It's a simple edit to change all of the 'private' members to 'protected'.