I don't see a shortcut key listed. Having to reach and use the mouse just to access the Quick Add Task field doesn't seem right :) "a" and "q" are unassigned?
While on the topic, a shortcut key to sort by Importance would be handy. It's the default sort (I think?), it's the one I find most useful. Being able to quickly return to that view would save another reach for the mouse and several clicks. "i" isn't used.
"esc" doesn't work to close the keyboard shortcut popup.