Question: I am running Gnome Shell with a 4k monitor and there are a few applications that I use that don't scale at all with the high resolution.

Here is an example of LMMS, an application that hasn't yet been ported Qt 5, so it doesn't have high dpi scaling capabilities:

[![Screenshot](https://i.stack.imgur.com/Af0Vr.jpg)](https://i.stack.imgur.com/Af0Vr.jpg)  

(Click images to enlarge)

Is there any way to scale a specific X window without changing the display resolution?

My current solution is to half the dimensions of my display resolution, but this degrades the resolution of every other application that supports proper dpi scaling:

[![Screenshot](https://i.stack.imgur.com/fJVFL.jpg)](https://i.stack.imgur.com/fJVFL.jpg)

Answer: 
I have an application that spawns many windows, and I cannot at the moment use `xpra` as is required by the accepted run\_scaled solution. I also can't tolerate gnome-tweak-tool's 2x scaling. Too huge. Need 1.5x.

I have discovered that the tigerVNC java client supports client-side display scaling of 150%.

So I start a vncserver with 2/3rds size and a minimal windows manager:

`vncserver -geometry 2520x1380 -xstartup ~/.vnc/xstartup-mwm`

I then connect with [TigerVNC's v1.7 java client](https://bintray.com/tigervnc/stable/tigervnc/1.7.0) (1.8.0 consistently crashes for me): 

`java -jar VncViewer-1.7.0.jar -ScalingFactor=150` 

Other than the commandline, you can hit `F8` to get the VNC Viewer Options. Screen->Scaling Factor->150%. This scales the resolution from 2/3rds of 4k to 4k.

[![enter image description here](https://i.stack.imgur.com/FldGV.png)](https://i.stack.imgur.com/FldGV.png)

Archaic MWM in VNC with 150% scaling on the left. Fancy Gnome desktop (native) on the right, no scaling. You'll notice the tiny icons. Gnome is otherwise adjusted for 4k with 1.5x Font Scaling in gnome-tweak-tool, but the icons don't scale. This is just an example application -- the icons and scaling in the application that is pushing me this way are far worse.

Unfortunately this is an entire 1.5x scaled desktop with a separate window manager. It creates a nice walled-off area for my multiwindow app, but it's annoying to have a second window manager. Nonetheless VNC is something I'm familiar with from longtime use, and this does kick over to the laptop pretty easily, so perhaps this is usable.
I think I've found a GPU-accelerated solution! Install `weston` and run this:

```
weston --xwayland --scale=2
DISPLAY=:1 your_app

```

That's it!

Tuning
------

Note 1: You may have noticed a magical number has been used, `DISPLAY=:1`. The underlying assumption here was that your main xorg display is `:0`. If it's not, adjust accordingly.

Note 2: You may have noticed that `weston` has a top panel by default. You may want to remove it. To do that, create a `weston.ini` file:

```
[core]
idle-time=0

[shell]
panel-position=none
locking=false

```

And use it when starting weston `weston --config=/path/to/weston.ini`. You can also place it to `~/.config/weston.ini` for it to be picked up by weston automatically, please refer to `man weston.ini` for further details.

EDIT: I've also documented the newly found approach here: <https://wiki.archlinux.org/title/HiDPI#Unsupported_applications,_via_weston>