[STUMP] Bug: Stumpwm crashes when raising a VirtualBox VM window

[Ernesto Alfonso]

Stumpwm crashes when raising VirtualBox VM

Stumpwm always crashes when raising a VirtualBox VM via a key shortcut, logging:
"Another window manager is running."

After redefining 'error-handler' to log the 'error-key', 'key-vals' as follows:

(defun error-handler (display error-key &rest key-vals &key asynchronous &allow-other-keys)
  "Handle X errors"
  (cond
    ;; ignore asynchronous window errors
    ((and asynchronous
          (find error-key '(xlib:window-error xlib:drawable-error xlib:match-error)))
     (dformat 4 "Ignoring error: ~s~%" error-key))
    ((eq error-key 'xlib:access-error)
     (write-line "Another window manager is running.")
     (write-line (prin1-to-string error-key) )
     (write-line (prin1-to-string key-vals))
     (throw :top-level :quit))
     ;; all other asynchronous errors are printed.
     (asynchronous
      (message "Caught Asynchronous X Error: ~s ~s" error-key key-vals))
     (t
      (apply 'error error-key :display display :error-key error-key key-vals))))

I can see the X error that is being generated:

Another window manager is running.
XLIB:ACCESS-ERROR
(:ASYNCHRONOUS T :CURRENT-SEQUENCE 28975 :MAJOR 33 :MINOR 0 :SEQUENCE 27255)
xinit: connection to X server lost

     
Steps to reproduce:

1) Using Debian Wheezy 7.6
2) Using VirtualBox 4.1.18_Debian_r78361
3) Start any virtual machine
4) Start firefox
5) Raise the VM while firefox is raised
6) Enjoy the crash

Curiously, this doesn't seem to happen when switching from certain other windows to the VM, eg terminal->VM, or emacs->VM. It only seems to happen when switching from firefox->VM.

Of course, there may be many more ways to reproduce this, but this is one.