diff -u trunk/panel-plugin/datetime.c bug4141/panel-plugin/datetime.c
--- trunk/panel-plugin/datetime.c	2008-06-08 19:17:04.000000000 -0700
+++ bug4141/panel-plugin/datetime.c	2008-06-21 12:51:40.000000000 -0700
@@ -186,6 +186,8 @@
   gchar *utf8str;
   gchar *format = NULL;
 
+  DBG("enter  (%d,%d) (%d)", x, y, keyboard_mode);
+
   switch(datetime->layout)
   {
     case LAYOUT_TIME:
@@ -205,6 +207,14 @@
   current = localtime((time_t *)&timeval.tv_sec);
 
   utf8str = datetime_do_utf8strftime(format, current);
+  DBG("%ld.%06ld (%s)", timeval.tv_sec, timeval.tv_usec, utf8str);
+
+#if USE_GTK_TOOLTIP_POSITION_WORKAROUND
+  if (x < 0 || y < 0) {
+    return FALSE;
+  }
+#endif
+
   gtk_tooltip_set_text(tooltip, utf8str);
   g_free(utf8str);
 
@@ -219,9 +229,89 @@
       (GSourceFunc) datetime_tooltip_timer, datetime);
   }
 
+
   return TRUE;
 }
-#endif
+
+#if USE_GTK_TOOLTIP_POSITION_WORKAROUND
+static inline void datetime_set_gtk_tooltip_timeouts(t_datetime *datetime,
+                    glong bmt, glong bt, glong t)
+{
+  GtkSettings *sp = datetime->gtk_settings;
+  if (sp == NULL) return; /* per documentation */
+  gtk_settings_set_long_property(sp, "gtk-tooltip-browse-mode-timeout", bmt, "datetime"); 
+  gtk_settings_set_long_property(sp, "gtk-tooltip-browse-timeout",       bt, "datetime"); 
+  gtk_settings_set_long_property(sp, "gtk-tooltip-timeout",               t, "datetime"); 
+}
+
+static inline void datetime_set_gtk_tooltip_timeouts_to_zero(t_datetime *datetime)
+{
+  datetime_set_gtk_tooltip_timeouts(datetime, 0, 0, 0);
+}
+
+/*
+ *  Default timeouts are from the documentation.
+ *  http://library.gnome.org/devel/gtk/stable/GtkSettings.html
+ */
+static inline void datetime_set_gtk_tooltip_timeouts_to_defaults(t_datetime *datetime)
+{
+  datetime_set_gtk_tooltip_timeouts(datetime, 500, 60, 500);
+}
+
+/*
+ * Event handler for:
+ * "enter-notify-event"
+ * "leave-notify-event"
+ * The tooltip timeouts are global to the panel process,
+ * so they are set to zero when the cursor enters the button widget's rectangle
+ * and restored to defaults when the cursor leaves.
+ */
+static gboolean datetime_enter_leave(GtkWidget        *widget,
+                                     GdkEventCrossing *event,
+                                     t_datetime       *datetime)
+{
+  switch(event->type)
+  {
+    case GDK_ENTER_NOTIFY:
+      DBG("GDK_ENTER_NOTIFY");
+      datetime_set_gtk_tooltip_timeouts_to_zero(datetime);
+      break;
+    case GDK_LEAVE_NOTIFY:
+      DBG("GDK_LEAVE_NOTIFY");
+      datetime_set_gtk_tooltip_timeouts_to_defaults(datetime);
+      break;
+    default:
+      DBG("unexpected event type");
+      break;
+  }
+  return FALSE;
+}
+
+static void datetime_connect_tooltip_timeout_settings_handlers(t_datetime *datetime)
+{
+  if (datetime->gtk_settings == NULL) /* init on first call */
+    datetime->gtk_settings = gtk_settings_get_default();
+  if (datetime->enter_notify_handler_id == 0)
+    datetime->enter_notify_handler_id = g_signal_connect(datetime->button, "enter-notify-event",
+                                          G_CALLBACK(datetime_enter_leave), datetime);
+  if (datetime->leave_notify_handler_id == 0)
+    datetime->leave_notify_handler_id = g_signal_connect(datetime->button, "leave-notify-event",
+                                          G_CALLBACK(datetime_enter_leave), datetime);
+}
+
+static void datetime_disconnect_tooltip_timeout_settings_handlers(t_datetime *datetime)
+{
+  if (datetime->enter_notify_handler_id != 0) {
+    g_signal_handler_disconnect(datetime->button, datetime->enter_notify_handler_id);
+    datetime->enter_notify_handler_id = 0;
+  }
+  if (datetime->leave_notify_handler_id != 0) {
+    g_signal_handler_disconnect(datetime->button, datetime->leave_notify_handler_id);
+    datetime->leave_notify_handler_id = 0;
+  }
+}
+#endif  /* USE_GTK_TOOLTIP_POSITION_WORKAROUND */
+#endif  /* USE_GTK_TOOLTIP_API */
 
 static void on_calendar_realized(GtkWidget *widget, gpointer data)
 {
@@ -467,10 +557,16 @@
       datetime->tooltip_handler_id = g_signal_connect(datetime->button,
                              "query-tooltip",
                              G_CALLBACK(datetime_query_tooltip), datetime);
+#if USE_GTK_TOOLTIP_POSITION_WORKAROUND
+      datetime_connect_tooltip_timeout_settings_handlers(datetime);
+#endif
       break;
 
     default:
       gtk_widget_set_has_tooltip(GTK_WIDGET(datetime->button), FALSE);
+#if USE_GTK_TOOLTIP_POSITION_WORKAROUND
+      datetime_disconnect_tooltip_timeout_settings_handlers(datetime);
+#endif
   }
 #endif
 
diff -u trunk/panel-plugin/datetime.h bug4141/panel-plugin/datetime.h
--- trunk/panel-plugin/datetime.h	2008-06-21 08:10:18.000000000 -0700
+++ bug4141/panel-plugin/datetime.h	2008-06-21 11:44:20.000000000 -0700
@@ -24,6 +24,15 @@
 
 #define USE_GTK_TOOLTIP_API     GTK_CHECK_VERSION(2,12,0)
 
+#if USE_GTK_TOOLTIP_API
+/*
+ * Workaround for bug 4141, which reports
+ * that the tooltip sometimes appears in the upper left corner of the display
+ * instead of over the datetime button widget.
+ */
+#define USE_GTK_TOOLTIP_POSITION_WORKAROUND 1
+#endif
+
 /* enums */
 enum {
   DATE = 0,
@@ -51,6 +60,11 @@
 #if USE_GTK_TOOLTIP_API
   guint tooltip_timeout_id;
   gulong tooltip_handler_id;
+#if USE_GTK_TOOLTIP_POSITION_WORKAROUND
+  GtkSettings *gtk_settings;
+  gulong enter_notify_handler_id;
+  gulong leave_notify_handler_id;
+#endif
 #endif
 
   /* settings */