KDE Font problem in Ubuntu 20.04

[Liam Proven]

On Wed, 21 Oct 2020 at 11:23, Christoph Pleger
<Christoph.Pleger at cs.uni-dortmund.de> wrote:
>
> Hm, obviously, the problem is really caused by the 3D acceleration setting in
> the the settings for the VirtualBox VM; when I disable the acceleration, the
> problem disappears.

I don't think that is a safe conclusion to draw. All we can say in
confidence is that the problem _occurs in association_ with VBox's
acceleration.

It works fine with every other 3D-composited desktop I've tried.

> But I wonder why the problem occurs with acceleration, I
> have the guest additions installed (I installed the manually, not from the
> distributed package), modules vboxvideo and vmwgfx are loaded,

Note that Vbox 3D is complicated. It is not VBox doing the
acceleration; it is VBox attempting to pass through the host systems'
3D acceleration functionality into the guest. Host/guest passthrough
is complex and difficult. It is mostly done in high-end server
hypervisors such as VMware, MS Hyper-V, KVM and so on -- and usually
then, the device passed through to the guest is dedicated to the
guest. With OpenGL passthrough, the graphics card must be shared with
the host, making it even more difficult.

So, it could be a bug in VBox, yes, but it could also be a bug in KDE
and the way it's calling OpenGL. I have also had problems with KDE in
VMs even with 3D disabled. I suspect it does odd nonstandard stuff
with 3D calls.

> and /var/log/
> Xorg.0.log says that the VMware driver is used.

There is a possible troubleshooting path there: VBox offers 2 or 3
different guest virtual graphics adaptors. Try the other ones?

My response to this problem is to avoid using 3D-rendered desktops in
VMs, at all, ever -- and to recommend to friends and colleagues that
they avoid using them as well.

The main 3D-rendered desktops are or were:
• Ubuntu Unity-3D (note 1: not the games programming toolkit of the
same name; note 2: there was a Unity-2D but it was discontinued)
• GNOME 3
• Cinnamon

The widespread ones that are not:
• MATE (can be enabled/disabled on demand)
• XFCE (ditto)
• LXDE/LXQt

KDE _says_ it can be disabled but when I have seen screen-corruption
issues, enabling/disabling compositing makes no visible difference.

I evaluate KDE periodically (along with all the other main desktops)
but the result of my evaluation is that I choose not to use KDE.

-- 
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