split screen to two fullscreen render window

Web
3

Thank you @Forrest, actually I tried to do that in the way you mentioned, seems like the constructor should be called like vtkFullScreenRenderWindow.newInstance(), but then putting { rootContainer: topDivElement } is not working.
This is what I tried:

div1 = document.createElement("div");
document.body.appendChild(div1);
fullScreenRenderer = vtkFullScreenRenderWindow.newInstance({rootContainer: div1});

console.log(fullScreenRenderer.rootContainer)

this prints out undefined.