Neal: Done. There are two LXDE-GDM choices and I have tried them both. I do have the old log-in screen back but it still asks. So unless it has a long time-out setting that I haven't been waiting for built in, the problem isn't solved.
In GDM Settings>General, Hide Visual Feedback is unticked, Disable Multiple Logins is ticked, Default session=Run Xclient script, and the 24 hour clock is used.
In GDM Settings>Local, Style is Themed with Face, and I have selected Theme=Selected only.