The screensaver_freedesktop Inhibit call only prevents the screensaver from activating during the lifetime of the calling process.  Unfortunately, since xdg-screensaver uses dbus-send to send the request, it expires as soon as the dbus-send process terminates.

Therefore, this patch changes the screensaver_freedesktop to use SimulateUserActivity in a screensaver_suspend_loop.

The ideal solution would be to change the specification for the D-Bus interface to either allow an option "OnBehalfOf" argument for the Inhibit method call or to add a new method allowing an application to send a request for another application.  The D-Bus interface for the screensavers seems to have been created by freedesktop.org, so perhaps the Portland group can apply some pressure to the D-Bus interface designers so that we can finally have one application that allows interfacing with all screensavers--even those that don't, and won't ever, support D-Bus (like xscreensaver).

---
 xdg-screensaver |   98       42 +      56 -    0 !
 1 file changed, 42 insertions(+), 56 deletions(-)

--- xdg-screensaver-cvs-1.48	2010-08-28 21:34:19.000000000 -0400
+++ xdg-screensaver	2010-08-28 21:33:52.000000000 -0400
@@ -540,37 +540,50 @@
   cleanup_suspend
 }
 
+screensaver_suspend_loop()
+{
+  lockfile
+  test "${TMPDIR+set}" = set || TMPDIR=/tmp
+  tmpfile=`mktemp $TMPDIR/tmp.XXXXXXXXXX`
+  # Filter stale entries from the xdg-screensaver status file
+  cat "$screensaver_file" 2> /dev/null | (
+    IFS_save="$IFS"
+    IFS=":"
+    while read wid pid; do
+      if ps -p "$pid" 2> /dev/null | grep xprop > /dev/null; then
+        echo "$wid:$pid"
+      fi
+    done
+    IFS="$IFS_save"
+  ) > $tmpfile
+  if [ -s "$tmpfile" ] ; then
+    # Suspend pending, don't do a thing
+    $MV "$tmpfile" "$screensaver_file"
+    unlockfile
+    return
+  fi
+  $MV "$tmpfile" "$screensaver_file"
+  unlockfile
+  (while [ -f "$screensaver_file" ]; do $*; sleep 50; done) > /dev/null 2> /dev/null &
+}
+
 screensaver_freedesktop()
 {
     case "$1" in
         suspend)
+        screensaver_suspend_loop \
         dbus-send --session \
                   --dest=org.freedesktop.ScreenSaver \
                   --type=method_call \
-                  --print-reply \
-                  --reply-timeout=2000 \
                   /ScreenSaver \
-                  org.freedesktop.ScreenSaver.Inhibit \
-                  string:$window_id \
-                  string:xdg-screensaver \
-                  | grep uint32 | cut -d ' ' -f 5 >| "$screensaver_file.cookie" \
+                  org.freedesktop.ScreenSaver.SimulateUserActivity \
                   2> /dev/null
         result=$?
         ;;
 
         resume)
-        if [ -f "$screensaver_file.cookie" ] ; then
-            value=`cat "$screensaver_file.cookie"`
-            dbus-send --session \
-                      --dest=org.freedesktop.ScreenSaver \
-                      --type=method_call \
-                      /ScreenSaver \
-                      org.freedesktop.ScreenSaver.UnInhibit \
-                      uint32:$value \
-                      2> /dev/null
-            rm -f "$screensaver_file.cookie"
-        fi
-        result=$?
+        # Automatic resume when $screensaver_file disappears
+        result=0
         ;;
 
         activate)
@@ -594,17 +607,12 @@
         ;;
 
         reset)
-        if [ -f "$screensaver_file.cookie" ] ; then
-            value=`cat "$screensaver_file.cookie"`
-            dbus-send --session \
-                      --dest=org.freedesktop.ScreenSaver \
-                      --type=method_call \
-                      /ScreenSaver \
-                      org.freedesktop.ScreenSaver.UnInhibit \
-                      uint32:$value \
-                      2> /dev/null
-            rm -f "$screensaver_file.cookie"
-        fi
+        dbus-send --session \
+                  --dest=org.freedesktop.ScreenSaver \
+                  --type=method_call \
+                  /ScreenSaver \
+                  org.freedesktop.ScreenSaver.SimulateUserActivity \
+                  2> /dev/null
         result=$?
         ;;
 
@@ -684,33 +692,6 @@
     esac
 }
 
-screensaver_suspend_loop()
-{
-  lockfile
-  test "${TMPDIR+set}" = set || TMPDIR=/tmp
-  tmpfile=`mktemp $TMPDIR/tmp.XXXXXXXXXX`
-  # Filter stale entries from the xdg-screensaver status file
-  cat "$screensaver_file" 2> /dev/null | (
-    IFS_save="$IFS"
-    IFS=":"
-    while read wid pid; do
-      if ps -p "$pid" 2> /dev/null | grep xprop > /dev/null; then
-        echo "$wid:$pid"
-      fi
-    done
-    IFS="$IFS_save"
-  ) > $tmpfile
-  if [ -s "$tmpfile" ] ; then
-    # Suspend pending, don't do a thing
-    $MV "$tmpfile" "$screensaver_file"
-    unlockfile
-    return
-  fi
-  $MV "$tmpfile" "$screensaver_file"
-  unlockfile
-  (while [ -f "$screensaver_file" ]; do $*; sleep 50; done) > /dev/null 2> /dev/null &
-}
-
 screensaver_gnome_screensaver()
 {
 # TODO
@@ -719,6 +700,11 @@
 # http://cvs.gnome.org/viewcvs/gnome-screensaver/src/gs-listener-dbus.c?rev=1.36&view=log
 # A problem seems to be that Inhibit is tied to the lifetime of the DBUS appname and
 # this can not be used from a script
+#
+# SimulateUserActivity can be used in a screensaver_suspend_loop, as with the
+# screensaver_freedesktop, above, so enabling the dbus interface in GNOME
+# probably just requires determining when to use dbus and when to use
+# gnome-screensaver-command
     case "$1" in
         suspend)
         screensaver_suspend_loop gnome-screensaver-command --poke