I only changed calls that are not exported as syscalls. I'm not sure how safe it is to add parameters to actual NtUser calls, and I didn't want to take the risk.
I quickly tested NtUserGetWindowRgnEx for instance, which has an unknown parameter, but it looks like it's a flag and it doesn't look like the function can take a DPI (and it may not be necessary to in the end, after some window surface refactoring).
Alternatively we could wrap driver calls with NtUserSetDpiAwarenessContext everywhere, but that looks awful IMO.