Hide a gadget until an event occurs

How do I had a gadget until an event occurs?
Such as hide a button until a text is entered into a text box.
essentially, I want to enable/disable a button from view until a certain event I want to happen occurs! How do you do this?
If it is not possible with Groov, will it be in the future?

I don’t think we have any visibility gadgets (or the ability to change visibility of gadgets) yet. I would certainly like to put this on the wish list.

Nice idea guys. We will make sure its on the list.