[arch-general] LXQT: Unable to find an X11 visual which matches EGL config

[Gabriel E.]

> A question about Qt/LXQT.
> 
> When starting LXQT with startlxqt LXQT crashes giving a core dump and
> showing in the systemd logs the message
> 'Unable to find an X11 visual which matches EGL config'
> 
> The setup is connecting from a Windows 10 client to a system running 
> Arch Linux using (x)rdp.
> 
> On the Arch Linux system lxqt is started from ~/.xinitrc.
> But a (x)rdp session is not created because of the above error.
> 
> Changing 'exec startlxqt' into 'exec xterm' in ~/.xinitrc does indeed 
> create a xrdp session but of course with just a xterm window.
> Calling any Qt program in this terminal window leads to a core dump and 
> that message
> 'Unable to find an X11 visual which matches EGL config'
> suggesting it's caused by Qt.
> 
> Last weekend 6 Januari I did a pacman -Syu and Qt was updated to version 
> 5.10.0.
> 
> Does anybody have an idea what change in Qt may be causing this error ?
> 
> Regards, Harm-Jan

Qt (and also GTK) use OpenGL to render and EGL is part of OpenGL. Xterm 
renders itself via Xlib, which doesn't need OpenGL. I would suggest 
installing Mesa onto the Linux system, because Mesa is what X11 uses for 
OpenGL. But I am not sure, it my also be possible to pipe OpenGL over RDP.