<tree string="Tasks" editable="bottom">
<field name="name"/>
<field name="user_id"/>
+ <field name="date_deadline"/>
+ <button name="do_open" states="pending,draft,done,cancelled" string="Start Task" type="object" icon="gtk-media-play" help="For changing to open state" invisible="context.get('set_visible',False)"/>
+ <button name="action_close" states="draft,pending,open" string="Done" type="object" icon="terp-dialog-close" help="For changing to done state"/>
</tree>
</field>
</page>