diff --git a/htdocs/lib/lib_rare.js b/htdocs/lib/lib_rare.js
new file mode 100644
index 00000000000..2ff38454804
--- /dev/null
+++ b/htdocs/lib/lib_rare.js
@@ -0,0 +1,22 @@
+// Copyright (C) 2009 Laurent Destailleur  <eldy@users.sourceforge.net>
+//
+// Script javascript that contains functions not frequently used
+//
+// \file       htdocs/lib/lib_rare.js
+// \brief      File that include javascript functions not frequently used (included if option use_javascript activated)
+// \version    $Revision$
+
+
+// in [-]HH:MM format...
+// won't yet work with non-even tzs
+function fetchTimezone() {
+	// FIXME: work around Safari bug
+	var localclock = new Date();
+	// returns negative offset from GMT in minutes
+	var tzRaw = localclock.getTimezoneOffset();
+	var tzHour = Math.floor( Math.abs(tzRaw) / 60);
+	var tzMin = Math.abs(tzRaw) % 60;
+	var tzString = ((tzRaw >= 0) ? "-" : "") + ((tzHour < 10) ? "0" : "") + tzHour +
+		":" + ((tzMin < 10) ? "0" : "") + tzMin;
+	return tzString;
+}