Linux: update xdg-utils again, and check in the built versions of the scripts.

scripts/xdg-icon-resource

 #!/bin/sh
 #---------------------------------------------
 #   xdg-icon-resource
 #
 #   Utility script to install icons on a Linux desktop.
 #
 #   Refer to the usage() function below for usage.
 #
 #   Copyright 2009-2010, Fathi Boudra <fabo@freedesktop.org>
 #   Copyright 2009-2010, Rex Dieter <rdieter@fedoraproject.org>
@@ skipping 382 matching lines @@
 #--------------------------------------
 # Checks for known desktop environments
 # set variable DE to the desktop environments name, lowercase
 
 detectDE()
 {
     if [ x"$KDE_FULL_SESSION" = x"true" ]; then DE=kde;
     elif [ x"$GNOME_DESKTOP_SESSION_ID" != x"" ]; then DE=gnome;
     elif `dbus-send --print-reply --dest=org.freedesktop.DBus /org/freedesktop/DBus org.freedesktop.DBus.GetNameOwner string:org.gnome.SessionManager > /dev/null 2>&1` ; then DE=gnome;
     elif xprop -root _DT_SAVE_MODE 2> /dev/null | grep ' = \"xfce4\"$' >/dev/null 2>&1; then DE=xfce;
-    elif [ x"$DESKTOP_SESSION" == x"LXDE" ]; then DE=lxde;
-    else DE=""
+    fi
+
+    if [ x"$DE" = x"" ]; then
+      # fallback to checking $DESKTOP_SESSION
+      case "$DESKTOP_SESSION" in
+         LXDE)
+           DE=lxde; 
+           ;;
+         xfce|xfce4)
+           DE=xfce;
+           ;;
+      esac
+    fi
+
+    if [ x"$DE" = x"" ]; then
+      # fallback to uname output for other platforms
+      case "$(uname 2>/dev/null)" in 
+        Darwin)
+          DE=darwin;
+          ;;
+      esac
+    fi
+
+    if [ x"$DE" = x"gnome" ]; then
+      # gnome-default-applications-properties is only available in GNOME 2.x
+      # but not in GNOME 3.x
+      which gnome-default-applications-properties 2> /dev/null || DE="gnome3"
     fi
 }
 
 #----------------------------------------------------------------------------
 # kfmclient exec/openURL can give bogus exit value in KDE <= 3.5.4
 # It also always returns 1 in KDE 3.4 and earlier
 # Simply return 0 in such case
 
 kfmclient_fix_exit_code()
 {
@@ skipping 420 matching lines @@
 if [ x"$update" = x"yes" ] ; then
     update_icon_database "$xdg_base_dir"
     if [ -n "$dot_icon_dir" ] ; then
         if [ -d "$dot_icon_dir/" -a ! -L "$dot_icon_dir" ] ; then
             update_icon_database $dot_base_dir
         fi
     fi
 fi
 
 exit_success