Please bear with me, kind of a corner case.

I can start twm OK with my ~/.twmrc in runlevel 3.

I can also start (in runlevel 3) blackbox, fluxbox, windowmaker and from there start twm (i.e., switch to twm without restarting X).

But not from fvwm.

The log then says:Obviously <some font> is set either in my ~/.twmrc or by default by twm, and I have checked that output of be not empty.

That seems to be a long standing bug in twm although I don't know if it was ever reported upstream, for instance https://ubuntuforums.org/showthread.php?t=1596636 and https://bugzilla.redhat.com/show_bug.cgi?id=446001

What puzzles me is that here it is only triggered (at least in runlevel 3) if I switch to twm from fvwm.

This also occurs if e.g. I do:
start fvwm => fluxbox => twm
but not if I do:
start fluxbox => twm

The workaround "LANG=C startx" works but is of course unacceptable as it prevents any further localization.

As always, any clue appreciated.

PS disregard this line in above output:
-1-ISO106476gb2312.1900-0
It seems due to usage of lxpanel and not in concern for the issue.

Do you have to mess around with all those half-assed window managers? Can't you settle on one?

Well, this is not for me, but for future users of Slint 14.2.

Al these windows managers are perfectly usable, including twm, when properly configured.

They will have a default configuration making them usable "out of the box" even by novice users, while allowing all users to configure them as they see fit.

This includes an auto-refreshed applications menu in the root menu

They will also get a (removable) panel with a menu, a tray with a notification area, a desk changer, applications launchers and a task bar. Probably an autostart too.

Thanks anyway for your post, clues to solve the issue even more welcome.

When did this bug occurred? Was it working as expected before?

Either there is a bug in twm, or given the LANG settings, you hit this libX11 bug:
https://www.linuxquestions.org/quest...te-4175592995/

1 members found this post helpful.

I just recently tried to start twm from fvwm without killing X, so I don't know.

Well, I have no display issue in xterm using an UTF-8 encoded locale.

But I checked that thg X log always ends with this:after starting fvwm and only fvwm, among the WMs shipped in Slackware, even when I use no panel. Also, gb2312.1980-0 is a Simplified Chinese font set

I know neither why this line appears in the log of the X server when I start fvwm nor why this disturbs only twm, but at least this gives me a hint. I will look at X font paths handling by the X font server and see if this line from fvwm is due to my specific configuration.

In that case, it looks like completely different bug. I was just a suggestion, because I was getting a lot of weird errors concerning fonts ("Could not create FontSet", "Can't ...something... fontmap", etc.) after libX11 upgrade and thought that maybe it could relate to your issue as well.

To completely rule out libX11 bug, does this happen on stable Slackware or current?

On stable Slackware.

Update.

I didn't find the origin of the issue.

But at least I have found a way to avoid its most severe consequence: in runlevel 4, using lxdm as display manager, after having used fvwm and logged out, twm wouldn't start until the machine be rebooted or the xserver killed.

To avoid that in lxdm's config I have set:
This resets the xserver after a logout, thus allowing twm to start.

Also as some features of lxpanel do not work or make sense with twm (windows minimization, task bar, virtual desktops manager), switching from another WM to it would be confusing anyway as the panel would be displayed with these (in this case not effective) features. So I just won't provide root menu entries to switch to/from twm without logging out.

I think it is acceptable. I don't mark this thread as [Solved] though as a workaround is not a solution.