This is all just patchwork to an old fso limitation. I'd rather just pick a default and deal with it until something like the chromium enabled builds can be used to build a real wide-screen interface through and through!
If textured borders are to be added, though, I'll place my vote for moddability.
EDIT:
I was on my phone for the original post and didn't view all the links. I am strongly opposed to borders on the mainhall screen or uh... something.. it just worries me because mainhalls are a highly specific interface. What if I make animorphic mainhalls and the player wants to use that but also wants non-stretched rest of the interface?
More importantly, what about all those mainhalls out there that are just menus and work great as widescreen, fullscreen, or whateverscreen? I guess my point is that there's a reason mainhalls have their own table opposed to the rest of the interface, they are a special situation and I suggest they be considered as such. I
do realize that people with supermadawesometriplemonitor setup will still want non stretched mainhalls. And I don't know what to do about it except to reiterate that this whole idea is a limitation to a limitation. It does nothing to actually
open FSO's super-limited interface code to the real future needs.