Add a wrapper function to get the desktop session.

usr/lib/mate-hud/mate-hud

@@ -16,7 +16,20 @@ from dbus.mainloop.glib import DBusGMainLoop
 from gi.repository import Gio, GLib, Gtk, Gdk, GObject
 from Xlib import display, protocol, X, Xatom, error
 
-if 'XFCE' in os.environ['XDG_CURRENT_DESKTOP']:
+def get_desktop_env():
+    desktop_env = ''
+    try:
+        desktop_env = os.environ['XDG_CURRENT_DESKTOP']
+    except:
+        pass
+    if not desktop_env:
+        try:
+            desktop_env = os.environ['XDG_SESSION_DESKTOP']
+        except:
+            pass
+    return desktop_env
+
+if 'XFCE' in get_desktop_env():
     try:
         gi.require_version("Xfconf", "0")
         from gi.repository import Xfconf
@@ -139,7 +152,7 @@ def terminate_appmenu_registrar():
     # TODO:
     #  - Use Dbus Quit method.
     #  - Add checks for other Desktop Environments.
-    if 'MATE' in os.environ['XDG_CURRENT_DESKTOP']:
+    if 'MATE' in get_desktop_env():
         if process_running('appmenu-registrar') and not process_running('appmenu-mate'):
             kill_process('appmenu-registrar')
     elif process_running('xfce4-panel'):
@@ -193,7 +206,7 @@ def get_menu(menuKeys):
     keyval, modifiers = Gtk.accelerator_parse(shortcut)
     shortcut = '' if modifiers else ',' + shortcut
 
-    desktop_name = os.environ['XDG_CURRENT_DESKTOP']
+    desktop_name = get_desktop_env()
 
     # Calculate display DPI value
     screen = window.get_screen()