Impressive that an operating system older than the DVD format can display a picture with more pixels compared to Full HD..
It's not that impressive. If you need a higher resolution than 256 x 256, it makes sense to support 65536 x 65536. No idea if there are any issues with that though, because some of the code might think all calculations can fit into a word and when you have windows wrapping off the left or right of the screen then you might run into problems.
The os can probably handle 8192 x 8192 without any problems. It should be possible to test this as most graphics cards can set up scrolling displays larger than your monitor.
