WebUpd8 reader KRK has updated the GNOME Shell Autohide Top Bar extension for GNOME Shell 3.2. The extension, initially created by fpmurphy, lets you hide the GNOME Shell top bar by double clicking it. To disable autohiding, double click the top bar again.

"Autohide Top Bar" is a new GNOME Shell extension created by fpmurphy to autohide the GNOME Shell Top Bar (panel) but it doen't just provide a simple autohide feature - the extension also lets you double click the Top Bar to toggle hiding on / off.