Concretely, I used an old > 1600x1200 21" CRT with Linux starting during the dot com crash, and was bummed when it died and I had to switch to low DPI flat panels.

I don't use KDE, but I've been told Qt apps are supposed to scale better on HiDPI.

I don't use KDE, ...

Or should we say that Cinnamon on Fedora doesn't work for you, on your hardware instead of dismissing something that many of us prefer to any other operating system, paid or free?

Edit: I'm a bit fed up with people writing like they can decide what is good or not.

I have used Windows since 1995, Linux since at least 2003, Mac (full time for both work and personal) for almost 3 years around 2010. FTR I was enthusiastic about getting a Mac, paid more for software than I'd ever done before, got my employer to pay for extra screen, keyboard, mouse and I think even an extra trackpad. For me it was a huge disappointment and I suffered through the last year after finally admitting it didn't work for me.

I have my opinions. I don't say you cannot prefer something else, but I will not accept other peoples authority to decide which OS is best for me and everyone else.

Edit2: as usual I don't mind the downvotes but I ask you to please tell me what I did to deserve them.

The fact is, it's not uniformly supported yet across Linux distros. Qt apps should theoretically be DPI-aware, but that's no guarantee either. See the various bugs filed against VLC, for instance: https://trac.videolan.org/vlc/ticket/17823

If your goal is to prove that it can be done, then I'm sure you'd be perfectly happy with KDE or KaOS in order to prevent someone from downloading an app that might not be HiDPI compliant.

But for the average person, it might be more trouble than it's worth. Or they might not like KDE. In which case, my recommendation that it might be better to stick with 1080P for now still stands.

You state it like a fact. You say it with no reservation about this being a very high resolution display etc.

In my opinion it wouldn't be less serious if I said Mac and Windows aren't really there yet because their package managers really doesn't compare to apt. Note: I don't say this. (At least not anymore : )

But my HiDPI laptop brings me frequent pain that I wasn't anticipating and it's not clear there's even a path forward to solving those problems in a consistent way. It's a whack-a-mole problem.

Please share your list of annoyances, I want to help :)

Many applications use toolkits that are unable / unwilling to scale. Arduino IDE is a good example - lots of bugs filed about it, some fixes ostensibly out there, but I've spent hours with no success -- the UI is unreadably tiny on my 3yo 3200x1800 laptop.

You can tweak your desktop (I use KDE) and many (but not all) other applications to scale up, but as soon as you plug in a monitor with different characteristics (I frequently plug into a 22" 1600x1200 LCD) things are going to look horrendous on at least one of your screens.

If you fix those two, I'll come up with some more. :)

Try running

  xrandr --dpi 200

and restart Android IDE.

Second monitor: you need to render the second screen at High DPI and then downscale. Example script (with two monitors):

  xrandr --output eDP-1 --off
  xrandr --output DP-2-1 --left-of eDP-1
  xrandr --output DP-2-1 --right-of DP-2-2
  xrandr --output DP-2-2 --scale 1.5x1.5 --pos 0x0
  xrandr --output DP-2-1 --scale 1.5x1.5 --pos 2880x0

EDIT: Oh, and yes, the 'scaling support' feature was added into the version that I was trialling of arduino IDE a while back (I forget the #'s). It was meant to have been resolved, but I noted on the various forums that lots of people (including myself) couldn't get it to play nice. Investigations were on-going whether it was a KDE, xorg/wayland, nvidia, phase of the moon, or some other related problem.

Isn't that true on every platform?

Then there's image/graphic density; I can live with that.

If you put it in full screen the monitor gets adjusted and it's not an issue.

At the same time other games don't have the problem. For example I've been playing Stardew Valley and it works perfectly fine in windowed mode looking exactly the way you'd want it to.

But normal applications based on UIKit and not a GL surface or something else like that? It's perfect.

I'm assuming so.

I've been using KDE as primary environment on laptop & desktop since the late 1990's. At dayjob I have to suck it up and use Win7 - typically as a VM (local or remote) running over RDP or VNC - but occasionally native boot. It really breaks badly with high DPI, but it's quite an old OS. I rarely touch MS Windows 8(.1) but when I did, on this hardware, it was struggling to maintain sanity with scaling. I've avoided playing with MS Windows 10, and OSX -- of course, OSX tends to run on its own hardware, so has a bit of an advantage there. I do have a MBP somewhere, and could try cranking it up on the high-DPI 32" monitor ... but a) I'm happy to defer to the expertise of people who have done this and are more familiar with the platform, and b) it won't help me (as I'm not going to move platforms).

For me at least that is the only modern browser I want.

To be fair, neither is Windows. I've had nothing but trouble with scaling my 4k laptop display under Windows 10. Some apps pick up the scaling info and work correctly, others don't. Some apps scale their fonts correctly, but leave their (presumably pixel map) UI elements microscopic. Things get even screwier when I use it in extended desktop mode with my (larger) 1080p monitor. If the scaling is on, the monitor is unusable. If the scaling is off, the display is unusable.

Seems like the only company that got this transition right so far is Apple.

It really isn't, quite. I'm using a brand new Dell XPS 13 with the way-too-many-pixels option, and there are a lot of things that have to be tweaked, particularly if you're not running a mainstream desktop environment. Even with tweaks in place, there're places where proportions are off and/or UI elements are way too tiny.

I expect that things will improve within the working lifetime of this laptop, but it's definitely a problem at the moment.

I'd happily donate money to some kind of Linux Dealing With Too Many Pixels Initiative, if someone were going to put together an effort at putting developer time into all the miscellaneous issues and getting fixes into distros / applications / desktops / etc.

The other major hump to get over at the moment is that many of the distros are spending resources to switch to Wayland, and I imagine we'll need to let that transition stabilize first before we get the bulk of resources diverted to HiDPI support.

The latest generation Thinkpads have high res screens :)

> many of the distros are spending resources to switch to Wayland

High DPI support is vastly improved in Wayland, so that's a good thing!

This is a bit unfair. "Linux isn't there yet, if you use an unpopular DE".

This is such a sad statement about the quality of today's laptop keyboards. Of the laptops I can remember using the keyboard on the Thinkpad 701C "butterfly" was superior to that on the T20 and T42 in terms of key shape and stroke, and the T42 is superior to the X60. The keyboards on the (work-issued) Macbook Air 2012 and Macbook Pro 2013 are garbage by comparison.

I glimpse the future every time I use my smartphone, and it is stupid.

That's odd. I've got an Asus ZenBook (UX305FA) running Fedora 25 with Gnome. I'm using my BenQ BL2710PT at its regular 2560 x 1440 resolution and it looks great. Other than adjusting the brightness a little I didn't have to do any tweaks.

Only application that doesn't scale is yEd, but it's 3rd party closed sourve and it doesn't scale on OS X or Windows either.

Fedora 25, 200dpi screen, no issues whatsoever (works and looks way better than Windows!).

What issues are you having? Maybe they're easily solved.

In the meantime, I've found downscaling to be an excellent option.

Unfortunately, wayland doesn't work with my displaylink dock drivers, but you can't have something for nothing I suppose.

So then you might decide to use just the external monitors, and scale it back to 100%. That works pretty well, but Windows forces you to restart (or "Sign Out" and back in, which will close all of your programs and stuff you were working on) every time you change that scaling option. Great! Everything looks fine...until you disconnect the Surface from its dock. Now it's back to looking tiny, and to make use of the SP4 internal screen I've got to once again change the scaling, restart, etc.

People at work ask me why I'm always swearing whenever I come into board meetings. It's because I've just detached my SP4 to bring it into the meeting, and I've either got to drop everything I'm doing to restart and be able to use it during the meeting, or keep the 100% scaling to avoid restarting and squint at my SP4's screen during the meeting.

EDIT: Nevermind, I was thinking of WHr. If it is using a 12V adapter, that is plenty.

IIRC the MacBook Pro has a 3 cell battery, meaning that you'll get around ~76Wh from the battery (11.2V * 6800mAh).

It's not safe to assume that all laptops will have a 3 cell battery. They might have chosen to install a 2 cell battery, in which case the capacity would only be ~50Wh (7.4V * 6800mAh). That's 35% less capacity!

Tablets frequently have lower voltage batteries. The iPad 4 for example has 3 cells but they're all in parallel, so the voltage is only 4.2V.

For laptops the sweet spot seems to be 3 cells, and I'm not entirely sure why, apart from higher voltages requiring smaller traces/wires. Maybe due to the LCD backlight? The LCD from the iPad 4 actually requires ~12V for the backlight, so there's a buck boost converter somewhere on the iPad logic board for this.