AutoHide Item Pane
This is a feature of Awasu that is designed to automatically give you more space for web pages when you need it. It can be turned on and off in the Program Options (go to the Display tab, click on Channel windows and check/uncheck Auto-hide feed items).
The item pane can be brought back into view quickly by pressing F7. This, together with the auto-hide feed items option, means that you can have the maximum amount of space for browsing but also be able to quickly bring up the list of items for that channel. Or if you prefer to work from each channel's summary page, F9 will bring that up.