Add Customerlize Button in More Button List In Odoo

There're two commen type of actions in odoo: ir.actions.server,ir.actions.client_multi
1.Using ir.actions.server

<record model="ir.actions.server" id="xxxx">

        <field name="name">XXX</field>

        <field name="type">ir.actions.server</field>

        <field name="model_id" ref="model_XXX"/>

        <field name="state">code</field>

        <field name="code">self.do_somthing(cr,uid,ids,context)</field>        

</record>

2.Using ir.actions.act_window

<record model="ir.actions.act_window" id="xxx">

        <field name="name">xxxx</field>

        <field name="res_model">xxx.xxx</field>

        <field name="view_mode">tree,form</field>

        <field name="view_type">form</field>

        <field name="view_id" ref="xxx.xxxxx.xxxx">

        <field name="target">new</field>

<record>

about is two type of ir.actions. the first one you can execute your own python code at the server side using state type "code". the second one you can call an existing action in client side.
3.how to add button in "more"button list

<record model="ir.values" id="xxxx">

        <field name="name"></field>

        <field name="model_id" ref="xxx_xxxx">

        <field name="model">xxxx</field>

        <field name="key">action</field>

        <field name="key2">client_action_multi</field>

        <field name="value" eval="'ir.actions.act_window,'+str(ref('action_xxx_xx'))"/>

</record>