Problem when submiting a dynamic form

[ehsankh]

I'm using Smart GWT LGPL 5.0 & I've following code:

...

ComboBoxItem my_combo = new ComboBoxItem("name", "title");
my_combo.setOptionDataSource(new my_ComboBoxDataSource());

...

my_form.setAction("http://my-url");
my_form.setCanSubmit(true);
my_form.setFields(my_combo, my_submit_btn);

where my_ComboBoxDataSource extends class GwtRpcDataSource.
the problem is that when I submit the form by clicking on submit button, fetchData method of combobox datasource is executed for unknown reason (but form also submits correctly).
This code was working correctly on previous versions of smartgwt.
any idea?