As I said earlier, the easiest way to do this is by creating "enough" controls and then controlling them through property nodes. The nicest way of doing this for what you want is by dynamically registering for events. You can see some more details about this here. You can see a basic example of something resembling what you want here and a newer and better version of it in the Code Capture Tool. You should note that this is not about moving controls, but the same basic princinples apply - you can display specific controls, register for their mouse down or value change events and move them using property nodes.
You should just note that this might not be as simple as you might think. I knew what I was doing and creating something quite similar, getting it to work smoothly, documenting it, testing it and incorporating some requests took me over a day of work.
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