#527 reminded me that we have an "Open as secondary" option if you Ctrl+Click a page when another page is opened. That splits the screen in two vertically, with one page being below the other.
My assumption is that the pages are too vertically long most of the time to use that functionality, and that the UI is complicated enough without adding that to the mix. I am inclined to remove that functionality if no one uses it.
What do you guys think?