disappearing panel at bottom

[Jim Maas <jimmaasuk gmail com>]

I'm using the latest gnome-shell on Ubuntu 13.10 and really like it.  One question though.  On 13.4 I used to get a transparent panel at the bottom showing me what applications are running, usually when I hit the hot corner (I think!) .  Since upgrading I've seen it a couple of times but can not get it regularly, and have no idea how I got it visible.  Can anyone help ?

Thanks

Jim