"This is factually not true. Right now I'm sitting in front of a thinkpad connected to two monitors, all 3 displays have different DPIs. I can drag my windows around between them just fine. Everything works. I'm happy."
Funny thing about that: if you want them to be scaled correctly based on different factors for each monitor, then you need a compositor...
You and I have an opposite definition of "correct" in this context, perhaps neither of us should use it! See enriquto's comment above, this is subjective. To us, we expect a window of size WxH to be WxH pixels, regardless of display. That's my definition of handling it properly, and when I use Wayland that's what will happen.
I will (grudgingly!) concede that perhaps it's not "universally and obviously correct" that things stay the same number of pixels, if you concede that perhaps it's not "universally and obviously correct" for windows to be drawn in terms of points and scaled behind the scenes.
We don't though, I mean if you explicitly change the scaling factor. Of course if you don't change the scaling factor then your scaling would technically be correct.
You're right! I'm sorry! You said "scaled correctly" but I misinterpreted as "appear/behave correctly".
Before this discussion I didn't have the concept of "scaling" my windows.. because that doesn't make sense to me, and it's something I'd never want. So my scaling factor for everything would be 1. Given that, Xorg "scales" perfectly.
> Funny thing about that: if you want them to be scaled correctly based on different factors for each monitor, then you need a compositor...
No, you don't. And using a naive compositor is liable to make things blurry compared to the direct approach (the application requests the physical dpi for its current location and changes its vector drawing).
Yeah you do if you want to have the same window span across monitors. And if you have non-integer DPI scaling then things will probably always be either blurry or inaccurate, that is unavoidable.
Funny thing about that: if you want them to be scaled correctly based on different factors for each monitor, then you need a compositor...