Show Header only when see.

I have the question of how I can hide the header in creation mode and edit mode; want it to show only when they are referring to a form.

Try using the CSS class "oe_view_only" and could not.

        <form string="People" version="7.0">
          <header class="oe_view_only">
             <button string="Wait" name="button_assists" states="assigned" type="object"/>
              ....
          </header>
         ...
        </from>