Hi E.M,

You can add  button like this in you XML file.

<button name="action_from view" string="Open View" type="object"/> 

You need to define your view here

In Your py

def action_from view(self, cr, uid, ids, context=None):

"Your Code"

        return {

'type': 'ir.actions.act_window',

'view_type': 'form',

'view_mode': 'form',

'res_model': 'mail.compose.message'    # name of respective model,

'views': [(compose_form_id, 'form')],    # view id and type

'view_id': compose_form_id, # view id 

'target': 'new',

'context': context,

}

Thanks