I just tried that. Drag the bar in the middle, between the two open windows and you can make FR 3/4 screen or whatever you want.
Yeah, I see you’re right! That makes it a realistic option. I’ll give it a further trial. I have tended to overlap the two windows a little. The second window contains reference material such as quotes I like to use, links to Amazon reviews of books I like to refer to, and HTML boilerplate. Not sure that there’s any real advantage to the split, but maybe it will crop up in use.