[Rhythmbox-devel] another queue UI layout

[Jonathan Matthew <jonathan kaolin hn org>]

The basic song queue functionality is now pretty stable (except for drag and
drop, which I'm still avoiding, and double clicking on queue entries), so I 
thought I'd go back over the discussion and see what I'd missed.

One idea that came up a couple of times was displaying the queue where
the source list currently lives.  Rather than replace the source list,
which isn't really anything to do with queueing songs, I made them share
space:

	http://j.kaolin.hn.org/rhythmbox-left-side-queue.png

I was initially concerned that the queue wouldn't display enough
information, but after using it for a while, it seems to be OK.
I seem to be able to identify most songs in my full library (~40G) from
the first two seconds of audio, so the title should also be enough..

The visibility of the source list and the queue display are toggled
independently, and the pane down the left side disappears when neither
are visible.

All the code for the other layouts is still there, and now the
layout is selected with some ugly #defines in rb-shell.h.

enjoy,
-jonathan.