Index: openacs-4/packages/xowiki/tcl/form-field-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/form-field-procs.tcl,v
diff -u -r1.170 -r1.171
--- openacs-4/packages/xowiki/tcl/form-field-procs.tcl	18 Apr 2010 21:01:08 -0000	1.170
+++ openacs-4/packages/xowiki/tcl/form-field-procs.tcl	24 Apr 2010 13:36:00 -0000	1.171
@@ -81,8 +81,11 @@
 
   FormField instproc validate {obj} {
     my instvar name required
+
     # use the 'value' method to deal e.g. with compound fields
     set value [my value]
+    #my msg "[my info class] value=$value req=$required // [my set value]"
+
     if {$required && $value eq "" && ![my istype ::xowiki::formfield::hidden]} {
       my instvar label
       return [_ acs-templating.Element_is_required]
@@ -654,10 +657,21 @@
   file instproc entry_name {value} {
     return [list name file:[my name] parent_id [[my object] item_id]]
   }
+  file instproc value {args} {
+    if {$args eq ""} {
+      set old_value [[my object] form_parameter __old_value_[my name] ""]
+      #my msg "[my set value] -- $args // old_value = $old_value"
+      if {$old_value ne ""} {
+        return "-"
+      }
+    }
+    next
+  }
   file instproc convert_to_internal {} {
     my instvar value
 
-    if {[my value] eq ""} {
+    set v [my value]
+    if {$v eq "-" || $v eq ""} {
       # nothing to do, keep the old value
       set value [[my object] form_parameter __old_value_[my name] ""]
       [my object] set_property [my name] $value
@@ -706,6 +720,7 @@
 
   file instproc pretty_value {v} {
     if {$v ne ""} {
+      my instvar object
       array set "" [my entry_name $v]
       array set "" [$object item_ref -default_lang [[my object] lang] -parent_id $(parent_id) $(name)]
       set l [::xowiki::Link create new -destroy_on_cleanup \