Feature request: VTK callback from pvQVtkTclWidget()?

[Ryton]

<tl;dr>Does the pvQVtkTclWidget support a user interaction callback to the main program? From the code, I think it does not?</tl;dr>

Full story: pvQVtkTclWidget() is set up and commanded through TCL, without any feedback (afaik), its tricky / impossible (for me at least) to get the interactor feedback to the program.

There might be two main pathways to implement this:

1. Create a class that inherits from vtkCallbackCommand reimplementing Execute( vtkObject caller, unsigned long evId, void) and setting pointers to a client and/or call data as needed. When the class is implemented, it becomes the callback function.
2. Create a function with this signature: void f( vtkObject * caller, long unsigned int evId, void* clientData, void* callData) and, where needed, create a vtkCallbackCommand setting its callback to the function we have created.

Yet to my knowledge, neither is available in pvbrowser?

Do you have a suggestion on how to pass back a user interaction with this VTKwidget?
Say, a mouseover or mouseclick in the VTK-space, or even more specific: vtkPointPicker info?
As we do get position and click data in canvas (in C++), and the picking info in TCL (as a picker object) ,but this info on the object interaction -to my knowledge- is not available in C++?