Xubuntu 18.10 problem with dual-monitor dual-desktop configuration.

[Jeffery Small]

I apologize for posting thus to multiple mailing lists, but I've tried the
xfce4-dev and xubuntu user and developer lists and there has been no
replies.  I'm hoping someone on this list can offer some assistance.

I have a system that has been running fine for years under all past
versions of Xubuntu up through 18.04.  The dual monitors are configures
*without* Xinerama so that separate desktop sessions with separate
panels launch on each screen.

After the recent upgrade to Xubuntu 18.10, even though it is properly
configured, the second monitor is not being recognized.

However, the second monitor is actually active:
   * Upon boot it goes from black to a uniform grey (although, it is back
      to black after trying to start a second window manager)

   * The mouse can travel onto the second screen (pointer visible) and
      keyboard input (e.g., volume keys) are active

   * Xscreensaver displays on both monitors when it goes active

   * In a terminal window, issuing the command: "DISPLAY=:0.1 xfce4-terminal"
     displays the new terminal on the grey background of the second screen
I have tried to manually start an *xfwm4* window manager, xfdesktop
desktop and xfce4-panel panel on the second screen, with no success.
I have also tried to create a $HOME/.xinitrc file with the desired command
but this also fails.
I have provided a page at the following link with very detailed images
and notes on configuration, log files, command output, etc. so as not to
clutter up this post

   http://smallthoughts.com/xfce/xfce.html
So my questions are:
   * What changed between Xubuntu 18.04 and 18.10 that is keeping the OS
     from detecting the second screen and configuring it properly and
     what can I do to rectify the problem?

   * Supporting dual monitors with separate window managers seems like a
     common set-up, yet I can't find straightforward documentation on enabling
     this. Am I missing something?

   * What modifications do I need to implement to get this second screen
     and desktop configuration re-enabled?
Thanks for any help you can offer.

Regards,
-- 
Jeff
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