[Seaside] System Browser questions

[itsme213]

I have one SystemBrowser in my image which shows nested class categories in 
the left pane (based on common prefix), but when I do the normal
    Open/system browser
I don't get that feature. Is there something special I should do?

Also, how do I (conveniently) get a browser on a single category, or a 
single class, without wasting all that screen space on columns I don't need?

Thanks