fixed issue 715, thanks pgergo

VERSION

@@ -1 +1 @@
-Version 1.99.7 (2012-03-13 21:20:19) dev
+Version 1.99.7 (2012-03-13 21:35:53) dev

gluon/sqlhtml.py

@@ -816,6 +816,8 @@ class SQLFORM(FORM):
                 self.custom.widget.id = widget
                 continue
 
+            self.readonly = readonly
+
             if readonly and not ignore_rw and not field.readable:
                 continue
 
@@ -1023,6 +1025,8 @@ class SQLFORM(FORM):
           form.record_changed = None
         """
 
+        if self.readonly: return False
+
         if request_vars.__class__.__name__ == 'Request':
             request_vars = request_vars.post_vars