[ESS] How to tame a jumpy iESS buffer?

[John Haman]

I have a problem that can maybe best described with a video:

https://imgur.com/a/he1BLiN

This is an example of a common occurrence for me. I have a iESS buffer 
open in one window, and for some reason, random actions in another 
window cause the buffer to jump up. I think actually the point is being 
centered in the comint buffer, but I'm not sure.

I don't really know what is causing this, but it seems like various 
different actions lead to a jump in the comint buffer. In the video I 
posted, I used 'evil-next-visual-line' and 'evil-previous-visual-line' 
to cause the jump.

How can I keep the buffer locked (like Rstudio)?

Thanks,

John