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>

one more thing .....

the quickest method to create button in more button is like this:

<act_window id="act_qunar_product_expense_merge_wizard" name="Merge Wizard" src_model="product.expense" res_model="product.expense.wizard" key2="client_action_multi" target="new" view_mode="form" multi="True"/>

act_window is one of short format of actions. be careful about your src_model and res_model. src_model determine which model the button attach on,and res_model means which model you are using to attach. if you want to using button in tree view set multi true otherwise set it false.

have fun !