Opening .glade (v2.0) file using Glade 3.22.1

[jmb <jmb365 gmail com>]

It has been years since I used and developed a program using Glade
ver2.0 as shown by the header of the file created then:

<?xml version="1.0" standalone="no"?> <!--*- mode: xml -*-->
<!DOCTYPE glade-interface SYSTEM "http://glade.gnome.org/glade-2.0.dtd";>

However, I am unable to open it using the version I installed via
apt-get (in Ubuntu 18.04).  Clicking on the file name after launching
Glade does nothing. When I start glade from the command line, and click
on the file I get:

(glade:1516): GladeUI-WARNING **: 20:39:53.354: Couldnt recognize
GtkBuilder xml, skipping /home/..../glade2project1/program.glade

The last time I used Glade was in 2007, so it has been a while and my
skills very rusty.  What I am doing wrong?  Or is Glade3 not capable of
reading the older format?  Any help or advice would be very much
appreciated.  Thanks!

JMB