Use an object's position to trigger an event

Hi,

I am wanting to trigger a hide/show event based on another object's position.

What I have is a draggable object, which works fine. I have another object which I want to 'react' to the dagged position.

So, basically, when object 1 is dragged right (x+), hide object 2a/show object 2b. And vice-versa.

Do I need to use onMove? I've looked for help on onMove but what little I have found has been very confusing.

Thanks,

Justin