When switching to external monitor: fvwm 1.1.3 does not track size, fvwm 1.1.4 exits

[stef-available]

• Fvwm3 version
  fvwm3 1.1.3 (released) (arch AUR package fvwm3 1.1.3-1)
  fvwm3 1.1.4 (arch AUR package fvwm3, PKGBUILD modified for 1.1.4)

• xorg version
  xorg 21.1.21 (arch AUR xorg-server-tearfree 21.1.21-1)

• Linux distribution or BSD name/version
  Linux 6.17.9-arch1-1 (fresh install)

• Platform (run: uname -sp)
  Linux unknown

Expected Behaviour

When switching to an external monitor,
fvwm 1.1.3 should recognize the new screen size,
fvwm 1.1.4 should not exit.

Actual Behaviour

When switching to an external monitor,
fvwm 1.1.3 uses the now wrong previous screen size,
fvwm 1.1.4 exits.

Steps to Reproduce

Minimize config: Just one menu, mouse, window functions, DebugRandR True

Start xorg via startx (modesetting, as root) and fvwm3 -v via xinitrc.
-> fvwm appears on laptop's internal display at 1920x1200

Plug in external monitor into USB-C.
-> external monitor stays dark

Switch to external monitor: xrandr --output DP-3 --auto --output eDP-1 --off
-> laptop display goes dark, external monitor switches on, shows 3840x2160

If fvwm 1.1.3:

Behaviour: Windows maximize to upper left 1920x1200 part of the screen.
Expected: Windows maximize to full screen size of 3840x2160.

Switching back and forth between monitors does not help, fvwm continues to use 1920x1200.

Restarting fvwm while on external monitor helps, fvwm then tracks the size properly when switching between monitors.

fvwm3-output.log_1.1.3-commented.txt

If fvwm 1.1.4:

Behaviour: Fvwm seems to exit when switching to external monitor, xorg shuts down.
Expected: Fvwm continues running, preferrably also getting the screen size right.

fvwm3-output.log_1.1.4-commented.txt

Does Fvwm3 crash?

fvwm 1.1.3: no
fvwm 1.1.4: exits, coredumpctl list shows no file