ModuleSynchronous fvwmrearrange cause xserver crash

[heelsleeh]

Thanks for reporting your bug here! The following template will help with
giving as much information as possible so that it's easier to diagnose and
fix.

Upfront Information

Please provide the following information by running the command and providing
the output.

• Fvwm3 version (run: fvwm3 --version)
  1.0.5

• Linux distribution or BSD name/version

• Platform (run: uname -sp)
  X86_64

Expected Behaviour

What were you trying to do? Please explain the problem.
Not to crash

Actual Behaviour

How to reproduce:
Open fvwm console and type
ModuleSynchronous fvwmrearrange
Hit enter, xserver will terminate immediately

What should have happened, but didn't?

Enabling logging

fvwm3 has a means of logging what it's doing. Enabling this when
reproducing the issue might help. To do this, either change the means fvwm3
is started by adding -v as in:

fvwm3 -v

or, once fvwm3 has loaded, send SIGUSR2 as in:

pkill -USR2 fvwm3

The resulting logfile can be found in $HOME/.fvwm/fvwm3-output.log

Steps to Reproduce

How can the problem be reproduced? For this, the following is helpful:

• Reduce the problem to the smallest fvwm configuration example (where
  possible). Start with a blank config file (fvwm3 -f/dev/null) and go from
  there.

• Does the problem also happen with Fvwm2?

Include your configuration with this issue.

Does Fvwm3 crash?

If fvwm3 crashes then check your system for a corefile. This is platform
dependant, however, check if:

• corefiles are enabled (ulimit -c)
• A corefile might be in $HOME or /tmp/.
• If you're using Linux (with systemd), check coredumpctl list.
  coredumpctl may need installing separately.

If you find a corefile, install gdb and run:

gdb /path/to/fvwm3 /path/to/corefile

If you're using coredumpctl then use:

coredumpctl debug

Then from within the (gdb) prompt, issue:

bt full

... and include the output here.

Extra Information

• Anything else we should know?

• Feel free to take a screen capture or video and upload to this issue if you
  feel it would help.

• Attach $HOME/.fvwm/fvwm3-output.log from the step above.

[ThomasAdam]

Hi @heelsleeh

Please can you try the ta/gh-784, and let me know if this fixes your issue or not?

[heelsleeh]

Hi @ThomasAdam , ta/gh-784 works fine now, thanks for the great work.