There is really no good reason to separate ground planes.
(At least not according to my professors at the university who specialize in EMC testing and EMC aware design.)
More info see this old post of mine:
This is the new “canvas” (=user interface)
It uses opengl to render the interface (hence the name)
It also will be the only canvas in future versions of kicad. (once all features have been ported)
The opengl canvas includes interactive routing and differential pairs. It also shows the mask layers.
But some features might be missing. (I never used legacy so i don’t really know of anything i miss.)