Dynamically get target element from the display element for checkbox cfs

The "id" var is a global variable that's shared the whole page, for pages
that have multiple checkbox cfs, previously changing any display element
would always change the value of the last hidden checkbox input, which the
final id value points to.

share/html/Elements/EditCustomFieldSelect

@@ -93,7 +93,8 @@
     var id = <% $name |n,j %>;
     id = id.replace(/:/g,'\\:');
     jQuery('#' + id + '-Display').change(function() {
-        jQuery('#' + id).val(jQuery(this).is(':checked') ? jQuery(this).data('checked-value') : jQuery(this).data('unchecked-value'));
+        var target = jQuery(this).attr('id').replace(/-Display$/, '').replace(/:/g,'\\:');
+        jQuery('#' + target).val(jQuery(this).is(':checked') ? jQuery(this).data('checked-value') : jQuery(this).data('unchecked-value'));
     });
 </script>
 % } else {