guixSD iterm-256colors 'screen; emacs -nw' and/or 'tmux; emacs -nw' color support

[myglc2]

I almost always run emacs in a gnu screen session.

For iterm-256color, in guixSD I have observed that ...

'screen; emacs -nw' ... supports 16 colors.

'tmux; emacs -nw' ... supports 8.

Not only does this seem a bit lame when you consider that VGA supported
256 colors circa 1988, it means that most emacs themes either look awful
or aren't usable.

I thought I might submit a patch to make 'screen; emacs -nw' support 256
colors. However, if there is a strong preference for tmux, maybe I will
switch to tmux and fix that instead.

Comments or recomendations would be most welcome. - Thanks, George