diff -urN lxsession-0.4.4.orig/lxsession-logout/lxsession-logout.c lxsession-0.4.4/lxsession-logout/lxsession-logout.c
--- lxsession-0.4.4.orig/lxsession-logout/lxsession-logout.c	2010-03-31 18:28:50.000000000 +0200
+++ lxsession-0.4.4/lxsession-logout/lxsession-logout.c	2010-07-14 00:10:28.000000000 +0200
@@ -25,6 +25,7 @@
 #include <glib/gi18n.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <signal.h>
@@ -72,6 +73,7 @@
     int ltsp : 1; /* under LTSP environment */
 } HandlerContext;
 
+static gboolean lock_screen(void);
 static gboolean verify_running(char * display_manager, char * executable);
 static void logout_clicked(GtkButton * button, HandlerContext * handler_context);
 static void shutdown_clicked(GtkButton * button, HandlerContext * handler_context);
@@ -83,6 +85,52 @@
 static GtkPositionType get_banner_position(void);
 static GdkPixbuf * get_background_pixbuf(void);
 
+/* Try to lock the screen, return TRUE on success, FALSE if no suitable
+ * screensaver was found or the screensaver command exited abnormally.
+ */
+static gboolean lock_screen(void)
+{
+    gchar *dummy;
+    gint exit_status;
+
+    if ((dummy = g_find_program_in_path("xscreensaver-command")) != NULL)
+    {
+        g_spawn_command_line_sync("xscreensaver-command -lock",
+                NULL,
+                NULL,
+                &exit_status,
+                NULL);
+    }
+    else if ((dummy = g_find_program_in_path("gnome-screensaver-command")) !=
+            NULL)
+    {
+        g_spawn_command_line_sync("gnome-screensaver-command --lock",
+                NULL,
+                NULL,
+                &exit_status,
+                NULL);
+    }
+    else if ((dummy = g_find_program_in_path("xlock")) != NULL)
+    {
+        g_spawn_command_line_sync("xlock -mode blank",
+                NULL,
+                NULL,
+                &exit_status,
+                NULL);
+    }
+    else
+    {
+        return FALSE;
+    }
+
+    g_free(dummy);
+
+    if (WIFEXITED(exit_status) && WEXITSTATUS(exit_status) == 0)
+        return TRUE;
+
+    return FALSE;
+}
+
 /* Verify that a program is running and that an executable is available. */
 static gboolean verify_running(char * display_manager, char * executable)
 {
@@ -187,6 +235,8 @@
 /* Handler for "clicked" signal on Suspend button. */
 static void suspend_clicked(GtkButton * button, HandlerContext * handler_context)
 {
+    lock_screen();
+
     if (handler_context->suspend_DeviceKit)
         dbus_DeviceKit_Suspend();
     else if (handler_context->suspend_HAL)
@@ -197,6 +247,8 @@
 /* Handler for "clicked" signal on Hibernate button. */
 static void hibernate_clicked(GtkButton * button, HandlerContext * handler_context)
 {
+    lock_screen();
+
     if (handler_context->hibernate_DeviceKit)
         dbus_DeviceKit_Hibernate();
     else if (handler_context->hibernate_HAL)
@@ -207,6 +259,8 @@
 /* Handler for "clicked" signal on Switch User button. */
 static void switch_user_clicked(GtkButton * button, HandlerContext * handler_context)
 {
+    lock_screen();
+
     if (handler_context->switch_user_GDM)
         g_spawn_command_line_sync("gdmflexiserver --startnew", NULL, NULL, NULL, NULL);
     else if (handler_context->switch_user_KDM)