Virtual Machines: High-DPI screen scale resets to 100% when I resize VM's window

Question

I've installed Ubuntu (tried 17.10 and 18.04 pre-release), since I have a 4k monitor I went to Settings - Devices - Displays and set Scale to 200%.

Everything looks fine until I resize a VM's window (including opening it fullscreen): Ubuntu resets the scale to 100% and everything becomes small.

How can I avoid this and "lock" the scale at 200%?

I tried this with VirtualBox and VMWare Player with the same results. I know there is a "scale factor" in VirtualBox's settings but it is not the same and it makes pictures blurry.

Solution

Fire up your terminal and type:

gsettings set org.gnome.desktop.interface scaling-factor 2

In virtualbox i tested it, and i can resize vm window without losing scaling. This applies to wayland, so 17.10 is best to test this.

Comments

[Pasi Suominen]

I tried with xorg, working on there too. Tested with virtualbox running on ubuntu 17.10

[0x574F4F54]

I found that for my 192dpi display that I needed to go the 'opposite' direction and set a scaling value of less than 1: xrandr --output Virtual1 --scale 0.5x0.5.

[Violet Giraffe]

It does make things larger, but unfortunately it only seems to up-scale the framebuffer resulting in blurry icons and fonts, this setting does not enable high-dpi rendering.

[Admin]

Tested on Ubuntu 20.04 and worked. Just note after executing the command, you need to resize the VM's window to see the effect.