Hi #Pascal

A button is not more that a way to execute an action call on the server, so if you wanna trace where the args are builded to call your button method you could see at do_execute_action function of /openerp/addons/web/static/src/js/views.js

Depending on the button action type it will be how the args get retrieved, for example a button type="object" it will call to the url "/web/dataset/call_button" that trigger the controller method call_button of the DataSet controller at /openerp/addons/web/controllers/main.py. A button type="action" it will call to the url "/web/action/load" that trigger the controller method load of the Action controller at /openerp/addons/web/controllers/main.py. For the workflow button type it will call to the url "/web/dataset/exec_workflow" that trigger the controller method exec_workflow of the DataSet controller at /openerp/addons/web/controllers/main.py

In your case it's a type="object" you could find that the [cr, uid] args get passed by the _call_kw method and the rest of the args came from the js function do_execute_action where for the type="object" it collect the record_id and the context to send it to the call_button url

Hope this helps to clarify the topic