Crash when X11 forwarding after re-attaching in tmux

[lassepe]

Migrating from JuliaGL/GLFW.jl#230

I frequently use GLFS as part of GLMakie from within a remote tmux ssh session via x-forwarding. That generally works quite well; however, it does not survive re-attaching. Indeed, the issue can be reproduced with a plain GLFW window (via GLFW.jl, which is just a Julia wrapper around the C library)

Steps to reproduce:

1. Connect to a ssh remote, e.g., ssh <user@hostname>
2. run tmux on the remote
3. Start a Julia REPL on the remote, run using GLFW; GLFW.Window()
4. Detach from the tmux session using CTRL+b, d
5. Disconnect from ssh client using exit
6. Re-connect to ssh client ssh <user@hostname>
7. Re-attach to tmux session tmux -u attach-session
8. Open another window GLFW.Window().

Step 8 here fails reliably with

XIO:  fatal IO error 2 (No such file or directory) on X server "localhost:10.0"
      after 212 requests (212 known processed) with 1111 events remaining.

I verified that the DISPLAY variable is set correctly upon re-attaching. I suspect, however, that maybe some socket is moved/re-created upon re-attaching which invalidates some GLFW internal state? In fact, if I start a fresh Julia session and load GLFW after re-attaching, things work as expected.