there is a small but annoying graphical bug that appears when opening or duplicating a file from an already opened Rhino file running in Full Screen mode:
When the new window is generated, there is a black letterboxing happening on top. When exiting and re-entering the Full Screen mode, the window fills the whole screen afterwards…
This is not a huge issue, but it is one that is here since RH5. Maybe this is a quick fix, that can be done during an enjoyable cup of coffee !