I play on a widescreen laptop (to be changing to a widescreen Mac) and I've had to go with making my own UIs all the time because there are a lack of Widescreen UIs out there.
Im guessing that all the possible replies will come from UI Creators who have 4:3 screens.
I got a gateway 19" wide but the vid card is kinda lame, my dog ate my good one.
Anyways, i play in window mode, emulate full screen at 1400 X 900 (wide)
and so therefore my collection i put togther on my portal, has the needed files to set ya up for that resolution if ya wanna.
I probably missed some, and some of those probably need a bunch of addons updated, but.....
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"You'd be surprised how many people violate this simple principle every day of their lives and try to fit square pegs into round holes, ignoring the clear reality that Things Are As They Are." -Benjamin Hoff, The Tao of Pooh