How to write a derived class of QwtSymbol?

[momo]

Hi all,

I meet a problem with QwtSymbol, I want to design some symbols so I have to write a derived class of QwtSymbol,
but It seems like that I need to access the PrivateData of parent class, and the Enumerated type Style of parent class doesn't include the style I designed, how could I write this derived class?

Please excuse me for my poor English, I am not good at it, but I am trying to improve it.

Momo