Hi Victor,
I encountered the same problem but my case is slightly different.
Inside EditForm template of ASPxGridView, I put two ASPxCombobox(es) which the first combobox has the following client side event to trigger CustomCallback event on the server.
<ClientSideEvents SelectedIndexChanged="function(s, e) {
ComboBox2.ClearItems();
GridView1.PerformCallback(s.GetValue());
}" />
The CustomCallback event is merely used to assign session variable which will be consumed by the ObjectDataSource of ComboBox2 to populate the items based on the value selected from ComboBox1. The problem is that whenever I choose an item from ComboBox1, the validation event of Combox2 is fired. So how could I prevent PerformCallback() from causing the validation of all controls inside the EditForm template.
P.S/ Both ComboBoxes have required validators.
Regards,
Thurein