title: Required attribute and validation groups
body: <p>I have several textboxes on the form that are marked with required="required" attribute (html5).
  There are two buttons. The first button should cause validation, the second should not.</p>
  
  <p>ValidationGroup doesn't work in this case.</p>
  
  <p>How is it possible to solve this issue?</p>
  
  <p>UPD: To use required attribute is the requirement so I cannot avoid it.</p>