Only use rw attributes for setting values.

app/assets/javascripts/app/controllers/_ui_element/ticket_perform_action.coffee

@@ -15,6 +15,9 @@ class App.UiElement.ticket_perform_action
 
         # ignore passwords and relations
         if row.type isnt 'password' && row.name.substr(row.name.length-4,4) isnt '_ids'
+
+          # ignore readonly attributes
+          if !row.readonly
             config = _.clone(row)
             elements["#{groupKey}.#{config.name}"] = config