Make fields with domain operator '=' becomes readonly.

Sent also readonly field for the creation of the record.
states attribute can not change the readonly attributes that is on the object.

tryton/gui/window/view_form/model/field.py

@@ -101,6 +101,8 @@ class CharField(object):
             if isinstance(state_changes, basestring):
                 state_changes = eval(state_changes)
             for key in ('readonly', 'required', 'invisible'):
+                if 'readonly' in self.attrs and self.attrs['readonly']:
+                    continue
                 if key in state_changes:
                     self.get_state_attrs(model)[key] = \
                             eval(state_changes[key], values)

tryton/gui/window/view_form/model/record.py

@@ -120,7 +120,7 @@ class ModelRecord(SignalEvent):
     def save(self, force_reload=True):
         self._check_load()
         if not self.id:
-            value = self.get(get_readonly=False)
+            value = self.get(get_readonly=True)
             try:
                 self.id = self.rpc.create(value, self.context_get())
             except Exception, exception:

tryton/gui/window/view_form/screen/screen.py

@@ -297,6 +297,8 @@ class Screen(SignalEvent):
                 field_dom = str(fields[dom[0]].setdefault('domain',[]))
                 fields[dom[0]]['domain'] = field_dom[:1] + \
                         str(('id', dom[1], dom[2])) + ',' + field_dom[1:]
+                if dom[1] == '=':
+                    fields[dom[0]]['readonly'] = True
         for node in xml_dom.childNodes:
             if node.localName == 'tree':
                 self.fields_view_tree = {'arch': arch, 'fields': fields}