vtk.js How to replace getApiSpecificRenderWindow in GenericRenderWindow?

Hello!

I consult the example ImageCroppingWidget, and an API of FullScreenRenderWindow called getApiSpecificRenderWindow is used.

Now I want to reappear this example in GenericRenderWindow, but there is no such API. My questions are what is available to replace getApiSpecificRenderWindow in GenericRenderWindow, and is there anything else to note when reappering ImageCroppingWidget in GenericRenderWindow?

Thank you a lot!

Contribution are welcome to edit and update GenericRenderWindow to use the more modern getApiSpecificRenderWindow instead of the WebGL specific implementation.