How do I get more mixers on the screen?

Hello,

How can I put the mixers on the screen as shown in the picture at http://media.arstechnica.com/guides/tweaks/linux-audio.media/ardour_ss.jpg ?
Normally there is only one mixer displayed, the others take the previous place when clicked on the respective track/bus.

It must be a small thing, but I missed it so far. :wink:

J.

Main menu: Window -> Show Mixer.
Or the shortcut: Alt-M.