diff -u --exclude='*.bak*' 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	2008-06-22 12:07:51.000000000 -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 +207,7 @@
   current = localtime((time_t *)&timeval.tv_sec);
 
   utf8str = datetime_do_utf8strftime(format, current);
+  DBG("%ld.%06ld (%s)", timeval.tv_sec, timeval.tv_usec, utf8str);
   gtk_tooltip_set_text(tooltip, utf8str);
   g_free(utf8str);
 
@@ -219,6 +222,12 @@
       (GSourceFunc) datetime_tooltip_timer, datetime);
   }
 
+#if USE_GTK_TOOLTIP_POSITION_WORKAROUND
+  if (x < 0 || y < 0) {
+    return FALSE;
+  }
+#endif
+
   return TRUE;
 }
 #endif
diff -u --exclude='*.bak*' 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	2008-06-22 11:16:48.000000000 -0700
@@ -23,6 +23,14 @@
 #define DATETIME_H
 
 #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 {