Disappearing desktops

Hi everyone,

I think this is my first post here, but I'm been using stumpwm for many
years.

I've downloaded and compiled the git development version as of Nov. 28,
2020 (C-t v shows version 20.11). It works perfectly except for one
problem (and I've had this same problem in the last few previous
versions). When using Virtualbox with a Windows 7 client, and with Linux
programs loaded on 2 of my 3 physical monitors, every time I leave the
group in which Virtualbox is loaded to do work in a different group,
when I return to the group in which Virtualbox is loaded, then one of
two things has happened:

(1) none of the programs, including those loaded in Virtualbox are
showing (the monitors showing Linux programs are completely blank), but
Virtualbox is showing, and if I click the Show button in Virtualbox the
programs instantly show up on all 3 monitors.

(2) all 3 monitors are completely blank, but with their programs still
in memory, and I have to issue the command to load Virtualbox which then
shows up and I can then click the Show button to see the others.

Not every time, but often, I will also encounter blank screens when
leaving and then returning to a group in which I only have Linux
programs loaded.

====================================

Here is the contents of my .initrc file, which your web site says you need:

#!/bin/sh

if [ -d /etc/X11/xinit/xinitrc.d ]; then
  for f in /etc/X11/xinit/xinitrc.d/*; do
    [ -x "$f" ] && . "$f"
  done
  unset f
fi

xrandr | /home/l/.screenlayout/3-horizontal.sh

exec /usr/local/bin/stumpwm

====================

Actually there is one other problem. (set-win-bg-color "black") in my
.stumpwmrc file no longer makes the background black, but only a light
grey. I would like for all screens of my display monitors in which no
programs are loaded to be solid black.

Is there any way to fix these two problems?

Lou