Yups its the resolution m8
I dunno about all the other UI's .. But with mine all you need to do is make the hotbars on the right 1x12 insted of 2x6 ,center up the target, group windows, active quest etc at the top, make the chat window on the left larger and the one at the top right also..
As for the backgrounds missing there is a transparent char settings file I have in the download you must be using that one I guess, Hit F10 if you see window backgrounds then, its fine, if not maybe you got a corupt download of the UI /shrug