diff -r 2a8a190f8aee -r 67a30d680f60 handlers.py
--- a/handlers.py	Sat Feb 14 20:13:26 2009 +0200
+++ b/handlers.py	Sun Feb 15 23:50:24 2009 +0200
@@ -115,11 +115,18 @@
     if request.is_post() :
         # update any modified preferences
         for pref in preferences.pref_list :
-            # get+parse new POST'd value
-            # XXX: this doesn't postprocess
-            new_value = pref.parse(request.get_post(pref.name))
+            # get the POST'd value, default = None
+            post_value = request.get_post(pref.name, None)
 
-            # update if changed
+            # skip non-specified values
+            # XXX: this is to not clobber timezone_offset to None
+            if post_value is None :
+                continue
+
+            # parse the POST'd value, None -> default
+            new_value = request.prefs.parse(pref, post_value)
+
+            # update if given and changed
             if new_value != request.prefs[pref] :
                 request.prefs.set(pref.name, new_value)
 
@@ -128,7 +135,6 @@
         req             = request,
         prefs           = request.prefs,
         preferences     = prefs,
-        timezones       = pytz.common_timezones,
     )
 
 def channel_select (request, channel) :