Ok, I found root of the problem:
```
class EngineObject : public QObject {
    Q_OBJECT
public:
    EngineObject();
    virtual ~EngineObject();
    virtual void process(const CSAMPLE *pIn, const CSAMPLE *pOut, const int iLen) = 0;
```

If I remove const here, I should be remove const in all child classes(it is about 20 classes!), and patch become VERY huge :)