For the next version of HoudahSpot, I am implementing a window which docks to the side of the screen where it shows and hides as needed. After looking into several implementations, I came up with my own. Seeing this may come in handy to some, I'd like to share this bit of code with you.

HHSlidingWindow allows for docking a window at an edge of the main screen. From there it may slide in and out of visibility. Its subclass HHAutoHidingWindow
provides automatic showing of the window as the mouse hits the screen edge where the window is hiding. The implementation is actually pretty straightforward.
It relies solely on tracking areas. No polling is done.