For the last decade I usually work in a full-screen mode terminal emulator (often xterm), and often with vertical split. The recent GNU Screen offers vertical split with ctrl-a |.
1280×720 offers 160 columns for typical 16px font (8px wide), just enough for two 80-column session. The same way, 1440x960 offers 160 columns for 18px fonts (9px wide). The larger one: 1920×1080 offers 240 columns, just enough for three 80-column session.
But in reality GNU Screen put a vertical bar to separate the sessions. The bar can be hidden or colored as background, but the space is taken. That leaves my console 79-columns, just one column short for daily work (e.g. coding convention requires each line less than 80 columns¹; auto-generated email reports assumed 80-column).
Is there a way to vacate the space of the vertical split bar? Or, if this can't be done, is any of the alternatives to GNU Screen, like Dvtm / Tmux, support vertical splict without a bar's space? An X terminal emulator that can do multiplex would fit the purpose as well, but such thing perhaps doesn't exist.
Note 1: Even Python programming language explicitly suggests 79 columns exactly for the purpose of unremovable marker at the 80th column, there are still other occassions that can take advantage of full 80-columns.