How can you scale the Gantt view?

In the documentation there is a mode tag that can be added to a gantt view. This tag allows you to scale the time duration of the gantt view. But it doesn't seem to do anything in reality. https://doc.openerp.com/trunk/server/03_module_dev_03/#id1 This code isn't rejected as an XML error, but it doesn't seem to scale the gantt view. How can you change the scale of a gantt view?