In the OS X version, double clicking an object does not select it. In fact the only way I have found to select an object is to randomly click at the very bottom of the screen. Doing so selects a random item. I just click in various parts of the bottom of the screen until the one I want is highlighted.
This is juts one of the many frustrations I've had with the OS X version. I would love to see a tutorial for it as the interface does not really resemble the iOS enough for the tutorials to apply.