How to get a SoF Target Mix pop up in a custom layout? [SOLVED]

[nofish]

When having 'Mix list' disabled in app settings, in the default layout that comes with the app, clicking on the button with the down arrow I get a pop up where I can select the sends on faders target mix.

How do I do this in a custom layout?

Thanks.

edit:
Solved. Needed to add a 'sidebar' element.