Start contributin and Error in startup script: couldn't connect to display ":0"

[Caio Barros]

Hello, everyone!

I'm looking into start contributing to lilypond. I can help with code and
also, yesterday I noticed that the website in some languages is missing the
link to the 64-bit unofficial version for Mac OS and I was told that
the portuguese translation is not maintained. I can help with that too. If
you have any urgent things that need to be done, please let me know.

Anyway, I'm trying to setup the lilydev container and when I try to run
lily-git I get the error in the email subject, i.e.

Error in startup script: couldn't connect to display ":0"

$DISPLAY both in the host and the container is ":0". I didn't have tcl/tk
installed on the host (I'm running Arch) but even after installing it, it
didn't work. Any suggestions? I'll try to run the VM for now.

Caio Barros