[vtkusers] callback set operations in C++

[Gregory Bleiker]

Hi 
I'm creating my own vtkInteractorStyle and am trying to set the callback functions, such as
SetLeftButtonPressMethod
Unfortunately, these functions are declared as
SetxyzMethod(void (*f)(void *), void *arg)
This means that the callback function has to be static member function as C++ class member functions can not be cast (except with quite some effort, see http://www.inquiry.com/techtips/cpp_pro/10min/10min0800.asp) 
Wouldn't it be more convenient to update the callback methods so class member functions can be easily set as callback even if they are not static?

Greetings
Gregi