title: Make a field invisible based on Many2one field value(name and not ID) in openerp 6.1
body: <pre><code>employee_category_m2o':fields.many2one('employee.transition.category','Category')
  </code></pre>
  
  <p>is my field. If user has selected Contract Labour in that <code>many2one</code> field then another char field '<code>grade</code>' should be made invisible.</p>