odoo14已经支持直接在tree视图顶部增加按钮，例如：

<record id="view_appointment_view" model="ir.ui.view">
  <field name="name">hospital.appointment.tree</field>
  <field name="model">hospital.appointment</field>
  <field name="arch" type="xml">
    <tree>
      <header>
        <button name="action_done" srting="Mark as Done" class="btn-primary" type="object"/>
      </header>
      <field name="name" />
      <field name="patient_id" />
      <field name="state" />
    </tree>
  </field>
</record>