Add REFRESH-TIME-ZONE

Fixes #476

stumpwm.texi.in

@@ -1895,6 +1895,7 @@ section.
 !!! ratrelwarp
 !!! ratclick
 !!! echo-date
+!!! refresh-time-zone
 !!! eval-line
 !!! window-send-string
 !!! reload

time.lisp

@@ -40,7 +40,8 @@
           *time-modeline-string*
           time-format
           echo-date
-          time))
+          time
+          refresh-time-zone))
 
 (defvar *time-format-string-default* "%a %b %e %Y %k:%M:%S"
   "The default value for `echo-date', (e.g, Thu Mar  3 2005 23:05:25).")
@@ -109,6 +110,15 @@
 
 (defcommand-alias time echo-date)
 
+(defcommand refresh-time-zone () ()
+  "Refresh the time zone information from the system.
+
+If you change the system time zone while StumpWM is running you can
+run this command to make StumpWM notice the change."
+  (sb-alien:alien-funcall
+    (sb-alien:extern-alien "tzset" (function sb-alien:void))))
+
+
 ;;; ------------------------------------------------------------------
 ;;; Helper functions
 ;;; ------------------------------------------------------------------