title: fvwm-menu-desktop hanging during menu creation and failing with python exception when using --get-menus
body: <p>I have upgraded to ubuntu 20.04 and have fvwm, I had the fvwm-menu-desktop that created the menus for me but lately it started behaving totally bad:</p>
  <p>(I use the command
   <code>fvwm-menu-desktop --desktop gnome --type gtk --theme masalla  --title FvwmKde</code> to generate my menu
  )</p>
  <ol>
  <li>it generates twice the menu</li>
  <li>it hangs half way (twice) just before creating the <em>Android Studio</em> menu item, (is that a hint?)</li>
  <li>when I try to check the desktop menus available, it throws a python exception error:</li>
  </ol>
  <pre><code>$ fvwm-menu-desktop --get-menus desktop
  Traceback (most recent call last):
    File &quot;/usr/bin/fvwm-menu-desktop&quot;, line 821, in &lt;module&gt;
      main()
    File &quot;/usr/bin/fvwm-menu-desktop&quot;, line 388, in main
      parsemenus(menulist, desktop)
    File &quot;/usr/bin/fvwm-menu-desktop&quot;, line 677, in parsemenus
      parsemenu(xdg.Menu.parse(menu), name, title)
    File &quot;/usr/lib/python3/dist-packages/xdg/Menu.py&quot;, line 1137, in parse
      return XMLMenuBuilder(debug).parse(filename)
    File &quot;/usr/lib/python3/dist-packages/xdg/Menu.py&quot;, line 641, in parse
      menu = self.parse_menu(tree.getroot(), filename)
    File &quot;/usr/lib/python3/dist-packages/xdg/Menu.py&quot;, line 659, in parse_menu
      self.parse_node(node, filename, menu)
    File &quot;/usr/lib/python3/dist-packages/xdg/Menu.py&quot;, line 668, in parse_node
      menu = self.parse_menu(child, filename)
    File &quot;/usr/lib/python3/dist-packages/xdg/Menu.py&quot;, line 659, in parse_menu
      self.parse_node(node, filename, menu)
    File &quot;/usr/lib/python3/dist-packages/xdg/Menu.py&quot;, line 668, in parse_node
      menu = self.parse_menu(child, filename)
    File &quot;/usr/lib/python3/dist-packages/xdg/Menu.py&quot;, line 659, in parse_menu
      self.parse_node(node, filename, menu)
    File &quot;/usr/lib/python3/dist-packages/xdg/Menu.py&quot;, line 691, in parse_node
      parent.Rules.append(self.parse_rule(child))
    File &quot;/usr/lib/python3/dist-packages/xdg/Menu.py&quot;, line 768, in parse_rule
      return Rule(type, tree)
    File &quot;/usr/lib/python3/dist-packages/xdg/Menu.py&quot;, line 421, in __init__
      self.code = compile(self.expression, '&lt;compiled-menu-rule&gt;', 'eval')
  ValueError: Name node can't be used with 'True' constant
  </code></pre>
  <p>I have
  Ubuntu 20.04
  fvwm 2.6.8 compiled on Jan 14 2019 at 19:59:25 with support for: ReadLine, RPlay, Stroke, XPM, SVG, Shape, XShm, SM, Bidi text, Xinerama, XRender, XCursor, XFT, NLS</p>
  <pre><code> mau  ~  python --version
  Python 2.7.18
   mau  ~  python3 --version
  Python 3.8.5
  </code></pre>
  <p>Thanks</p>