I have a widescreen, too. This is great for my private hobby/work, having 3-5 windows open with graphic/circuits/listings without a distracting artificial divide in the middle by a two screen solution is great. Incidentally, the wide screen is exactly two "ordinary" screens in pixels.
Factorio works well in full screen, like other games (I dont know how much a game has to be specially coded for resolutions, or the driver abstracts all). BUT - for me they are
hard to play in widescreen; it is a
long way to move the mouse between a menu on the left to something on the right, and back to the action in the middle. Putting some "display only" info on the edges though is great.
My suggestion/observation on "supporting widescreen":
1: Allow GUI panels to store their position after they have been moved, and not always start smack in the middle. In general all attributes (position, size, tab or scale setting in the GUI) should be saved.
1+: And that goes in particular for the hot/quickbar at the bottom. I am using plenty of shortcuts with the bar, so having all rows visible at one side would be "+1"
1b: And... leaving a GUI open (like the electric usage). That might be hard to implement but this is just a wish-list. (NB: always visible GUI panels appear under newly opened)
I can see there might a problem on how to reset locked settings, if a GUI appears offscreen, f.ex. due to moving a game between machines or changing screen. That could be handled by a reset button in the graphics setting.
2: What is with the zoom limit? With my full screen the max zoom (as shown in the debug info) it is ~0.5, and if I play in a tiny 1280x800 window it is ~0.25, ie double the zoom out. Is this a limitation of my system(graphics) or by design? It seems I have a greater zoom range on a smaller screen, but carefull checking of what is visble on far left and right is the same. but the vertical distance is halved. This seems "fair", game design wise (
viewtopic.php?p=386517#p386517) so I suspects it is by design.
OK, the last point was more an observation. It is fair but irritating, and I play Factorio in a window that is more of the 4:3 aspect. This leaves space for other windows (Mail, chat...)
Enough of this, I have to get back to the game, I am nearly done with the "lazy bastard" acheivement (104 objects handcrafted)