Well I've been working on this..

[Max Howell]

The concept is for the columns to scroll left as you drill down, as
you don't need them anymore. You shouldn't have to resize the window
really wide, things should disappear from view, although ideally not
too much as the hierarchy describes what you are looking at. Having to
scroll back is a bit of a bitch for sure, but you don't have to do
this often, and I plan to have some kind of shortcut for it, visual
shortcut I mean.

When playing I am considering having the context view expand to fill
the whole width, with the playlist or currently playing column showing
too. But I haven't really explored that yet.

Max