I wonder if a simple solution would be to put a filter on the UI output, which breaks its sections into quadrants, or whatever applies, and the reduces everything by 50%, and either push all pieces into their original placement by algorithmically compensating a number of pixels, directionally-appropriate per piece, based on the screen resolution - or, lock a single corner of each piece to its place on the screen, and then down-scale them all 50%, or maybe more.
Any part of the UI that's not stationary (stationary: minimap, character portraits, spellbar, chat box) doesn't need any attention to where it might move on the screen.
Any means that accomplishes the goal will bring satisfaction.
I don't want to keep falling out of my chair
every time I see this.
Pretty soon I'll have a broken spine.
A filter / wrapper approach will work just fine for the people playing with it - and if they ever change the engine, they can just remove it without digging into anything.