You're right, but even many builtin Microsoft apps - while they supported DPI scaling - did not support multi-DPI switching and rather than scaling properly just scaled pixels and looked blurry.

It's "not Windows fault", sure but it certainly makes it a worse experience than other platforms like OSX where multi-DPI is much more commonly supported.

I would much prefer the Windows behavior to what I see on Linux. Right now, if I open an app that doesn't support high DPI, it is just unusable because it is so tiny.

Couldn't you just manually reduce your screen resolution? Or is that too drastic to be worth it?

It's worth considering whether there is some flaw with windows multi dpi scaling such that apps don't use it. Firefox and Chrome have scaled properly on Mac for years now, while even Windows 10 ships with first party apps that don't scale right. (E.g. device manager.)

For sure that this has been an issue in the past with Windows. UWP helps make muli-DPI work by default in new applications.

Sure, but 99% of my Windows software isn't UWP. It's all good and well to say it's there, but that doesn't make the experience good for the user. Contrast to KDE and OS X where it just works for 99% of software.

I mean, I get it, same issue as Vista for Microsoft - people expect 100% backwards compatibility, but it turns out that terrible design decisions made many years ago tend to mean you need to break compatibility. Just like UAC, resolution scaling will be an issue that becomes less painful in Windows over time. Right now it's not great, however.

I mean, you say that, but on KDE, for example, every application except one on my system works with DPI scaling (the odd one out is Unity3D) - that's because at the QT level DPI scaling is built-in, so the toolkit supports it and the applications get it for free. Clearly this wasn't the case for the older Windows UI stuff, where they are literally just scaling the image of the window up (which means horrible looking text).

Actually, the really old windows stuff did support scaling - the 'Large fonts (120%)' option was there almost forever. I remember that original Delphi, circa 1995, supported it.

Just most apps chose to ignore it, the developers took the 'anyone uses 96 dpi anyway' attitude and at the end of 90's most applications started to suck at 120 dpi.

Yep, Windows API already had support for logical pixels in the 16 bit days and all good books always preached to convert between logical pixels and physical ones.

I guess people got lazy, as you say.

I think that the monitors stayed more or less the same later pixel density for a very long time. Is only been gradually increasing very slowly for 20 years, until a few years ago.

No point in spending time on logical pixels if it makes almost no relevant difference...

It's

Anything running its own renderer doesn't get to benefit from component scaling since they don't use components.

That was my point - running KDE, this is extremely uncommon, running Windows, it's practically every application.

The problem isn't just scaling between two different resolutions, it's the inconsistencies (yes, apps don't take advantage but that's not the only issue). For example, if I want 200% 4k (my monitor) and 100% 1080p (my 2 side monitors), I have to choose between ultra-tiny text on my 4k with regular text or blurry text on my 1080ps.

http://i.imgur.com/o1S8ZUt.png

Is that Windows 10? On my Windows 10 Ent desktop I'm able to set the scale factor of each display independently.

http://imgur.com/a/5378F

This is Windows 10. How do I enable that option?

Erm...click on the display you want to change (1,2,3) and simply drag the slider?

This month's Windows update fixes DPI scaling for old toolkits.