I have checked in a fix (http://git.savannah.gnu.org/cgit/screen.git/commit/?id=e5b296e8af899e199d8c416da7b6e7204824ed1b and next) that will try to 'Do The Right Thing' with layout commands when there's no display attached to it. So (1) it will not crash with layout commands with -dm, and (2) it will be possible to create multiple layouts and save their names. This is, at this point, not really useful, since you cannot split when detached. So more ideally, splits should be possible even where there are no displays (it will be tricky to determine the size of the splits, but maybe we can just start with the default 80x25 size).

So, in short, fixed. But keeping it open as a reminder to allow splitting when detached.

Does including NEED_DISPLAY in layout's line in comm.c is acceptable for 4.1.0?

diff --git a/src/comm.c b/src/comm.c
index 5f4af8a..862f915 100644
--- a/src/comm.c
+++ b/src/comm.c
@@ -213,7 +213,7 @@ struct comm comms[RC_LAST + 1] =
 #endif
   { "kill",            NEED_FORE|ARGS_0 },
   { "lastmsg",         CAN_QUERY|NEED_DISPLAY|ARGS_0 },
-  { "layout",           ARGS_1|ARGS_ORMORE},
+  { "layout",           NEED_DISPLAY|ARGS_1|ARGS_ORMORE},
   { "license",         NEED_LAYER|ARGS_0 },
 #ifdef LOCK
   { "lockscreen",      NEED_DISPLAY|ARGS_0 },

Steps to reproduce:
1. Use layout command in config (like "layout autosave" or "layout save d0")
2. Try to start screen detached: screen -d -m

$ screen -ls
There are screens on:
        8316.main       (Attached)
        9715.base       (Dead ???)
Remove dead screens with 'screen -wipe'.
2 Sockets in /tmp/screens/S-adam.