I would like to create a button action that opens the popup with the list view of the model of the relation and link it to the relation field. I want this so that it's 1 click less to open the popup and to keep both options.

The action is when you click a m2o relation and the second last option is "Search More...", clicking on it opens the relations model tree view with the search view. 

Can anyone show me an example. Don't even know for what to search for in the odoo source code.