[otrs] expand zoom view for customers

Hi all, one new feature in otrs is the expand zoom view feature. But it is only available in the agent webinterface. With this function it is possible to see all articles of a ticket at once. it is configurable in the config Frontend::Agent::Ticket::ViewZoom. We need this function for our customer webinterface too. Can someone explain me the way to do that, because i find no possibility to do that by configuring the system. Kind regards Thorsten