fvwm -r just terminates the current window manager, replace fails

[halfdog]

Binary package hint: fvwm

"fvwm -r" does not complain, that it cannot replace the running window manager (fvwm started from by xdm via " /usr/bin/ck-launch-session x-window-manager"), but attempt to replace running window manager causes current window manager to terminate (x-window-manager is symlink to fvwm2).

Restart via the fvwm menu item "Restart" works normally.

Description: Ubuntu 10.04 LTS
Release: 10.04

fvwm:
  Installed: 1:2.5.28.ds-3
  Candidate: 1:2.5.28.ds-3
  Version table:
 *** 1:2.5.28.ds-3 0
        500 http://archive.ubuntu.com/ubuntu/ lucid/universe Packages
        100 /var/lib/dpkg/status

[halfdog (halfdog)]

Attached debugger to both old fvwm and new one.

Old one terminates normally (exit code 0)

New one (started with fvwm2 --debug --debug-stack-ring) does not write any message to stderr/stdout, just terminates with exit status 1.